Ferugliotherium
Encyclopedia
Ferugliotherium is a fossil mammal
from the Campanian
and/or Maastrichtian
(Late Cretaceous
, around 70 million years ago) of Argentina
in the family Ferugliotheriidae
. The genus
contains a single species, Ferugliotherium windhauseni, which was first described in 1986. Originally interpreted as a member of the extinct mammalian group Multituberculata
on the basis of a single brachydont
(low-crowned) molar
, it was recognized as related to the hypsodont
(high-crowned) Sudamericidae
after the discovery of additional material in the early 1990s. After the discovery of a jaw of the sudamericid Sudamerica
in 1999, these taxa (collectively known as Gondwanatheria
) were no longer considered to be multituberculates and a few fossils that were previously considered to be Ferugliotherium were assigned to indeterminate multituberculates instead. Since 2005, a relationship between gondwanatheres and multituberculates has again received support. A closely related animal, Trapalcotherium
, was described in 2009 on the basis of a single tooth.
About twenty teeth and a jaw fragment have been referred to Ferugliotherium, but the assignment of many of these is controversial or has been superseded. The upper and lower incisor
s are long and rodent-like and have enamel
on only one side of the crown. A fragment of the lower jaw shows that the tooth socket
of the lower incisor was very long, extending below the fourth premolar
(p4). The p4 is preserved in this fragment; it is blade-shaped and resembles multituberculate p4s. However, the determination of this dentary fragment as Ferugliotherium is in question. The identity of a few additional isolated premolars assigned to Ferugliotherium, some also resembling multituberculates, is also uncertain. The first lower molariform (molar-like tooth; mf1) is known from four examples, of which two were originally identified as upper molars of a different species (Vucetichia gracilis), which is now considered a synonym
of Ferugliotherium. They bear two longitudinal rows of three or four cusps
and transverse crests and furrows. A single example each of the second lower (mf2) and first upper molariform (MF1) show that these teeth also had longitudinal cusp rows and transverse furrows and crests, but the mf2 had only two or perhaps three cusps per row and the MF1 had three longitudinal rows.
Although Ferugliotherium teeth are much lower-crowned than those of the Sudamericidae, they share an essentially similar pattern on the occlusal (chewing) surface of mf1 and mf2, similar incisors, backward jaw movement during chewing, and enamel with small prisms. Ferugliotherium is thought to have been a small animal, with a body mass of about 70 g (2.5 oz), and may have eaten insects and plant material. Its remains have been found in two formations of southern Argentina, where it is part of a mammal fauna that also includes the sudamericid Gondwanatherium
, a variety of dryolestoids, and the possible triconodont Austrotriconodon.
on the basis of a single second lower molar
(m2) from the Late Cretaceous
Los Alamitos Formation
of Argentina. The generic name, Ferugliotherium, honors Italian paleontologist Egidio Feruglio
. Bonaparte created a new family
, Ferugliotheriidae
, for the new species and tentatively assigned it to Multituberculata
, a group of mammals that was diverse during the late Cretaceous, mostly in the northern continents (Laurasia
), but is now extinct. In subsequent years, other finds permitted a more confident assignment to Multituberculata. In 1990, Bonaparte described Vucetichia gracilis on the basis of what he interpreted as two upper molars of a relative of Gondwanatherium
within the order Gondwanatheria
, a small mammalian group that was at the time known only from Argentinean fossils and thought to be related to xenarthra
ns within a group called Paratheria
. The generic name, Vucetichia, honors Argentinean paleontologist Guiomar Vucetich, and the specific name, gracilis (Latin for "slender"), refers to the animal's small size.
However, in 1990 David Krause and Bonaparte argued that Gondwanatheria, including Ferugliotherium (family Ferugliotheriidae), Gondwanatherium, and Sudamerica
(family Sudamericidae
), should be placed within Multituberculata. Two years later, Krause, Bonaparte, and Zofia Kielan-Jaworowska
described additional material of Ferugliotherium (which they tentatively placed in the multituberculate suborder Plagiaulacoidea) and suggested that the supposed upper molars of Vucetichia were in fact heavily worn first lower molariforms (mf1) of Ferugliotherium. In 1993, Krause described an unworn mf1 of Ferugliotherium and confirmed that Vucetichia was based on worn specimens of Ferugliotherium and therefore a synonym
of the latter. In the same year, he and Bonaparte argued once again that Ferugliotherium, Gondwanatherium, and Sudamerica formed a closely related group of mulituberculates, which they called the superfamily Gondwanatherioidea. Kielan-Jaworowska and Bonaparte described a lower jaw fragment with a multituberculate-like lower fourth premolar
(p4) from Los Alamitos and tentatively identified it as Ferugliotherium. On the basis of the morphological features of the jaw fragment, they argued that gondwanatherians are not closely related to any other multituberculate group, and consequently placed them in a suborder of their own, Gondwanatheria.
In 1999, Rosendo Pascual and colleagues described a jaw of Sudamerica. Because some of the features of this jaw were thought to be incompatible with a multituberculate identity, they regarded gondwanatheres (including Ferugliotherium) as Mammalia incertae sedis
. However, in 2009 Yamila Gurovich and Robin Beck argued in favor of a close relationship between gondwanatheres (including Ferugliotherium) and multituberculates. The controversy is partially due to disagreement over the assignment of two upper premolars and the jaw fragment described by Kielan-Jaworowska and Bonaparte in 1996; Gurovich and Beck identify these as Ferugliotherium, while Kielan-Jaworowska and others regard them as indeterminate multituberculates.
In the 2000s, some possible close relatives of Ferugliotherium were discovered. An enigmatic tooth from the Paleogene
of Peru, LACM 149371
, was described in 2004 as possibly related to the family Ferugliotheriidae. In 2007, Kielan-Jaworowska and colleagues described a p4 from the La Colonia Formation
(Late Cretaceous of Argentina) as a new multituberculate genus, Argentodites
, but Gurovich and Beck noted close similarities between this p4 and the p4 in the possible jaw fragment of Ferugliotherium and suggested that it represented Ferugliotherium or a closely related species. In 2009, a single mf1 from the Allen Formation
(Late Cretaceous of Argentina) was described as another ferugliotheriid genus, Trapalcotherium
.
Ferugliotherium is known from isolated teeth, the assignment of some of which is controversial. The material from the Los Alamitos Formation, which is mostly in the Museo Argentino de Ciencias Naturales Bernardino Rivadavia (MACN) in Buenos Aires
, with one tooth in the Museo de La Plata (MLP) in La Plata, Argentina, has been thoroughly described; while there are additional Ferugliotherium fossils from the La Colonia Formation, they have not been described in detail. Although the fragmentary nature of the known fossils of Ferugliotherium makes it impossible to determine its dental formula with certainty, Gurovich suggested that it had one incisor
(possibly two in the upper jaw), no canines, one or two premolars, and two molars on each side of the lower and upper jaws. However, on the basis of comparisons with Sudamerica, which is known to have had four lower molariforms (molar-like teeth, either premolars or molars) in its lower jaw, Pascual and Ortiz-Jaureguizar suggested in 2007 that Ferugliotherium may also have had four lower molars.
Ferugliotherium was much smaller than the sudamericids Gondwanatherium and Sudamerica, and its body mass is estimated to have been about 70 g (2.5 oz). Unlike the hypsodont
(high-crowned) sudamericids, Ferugliotherium has brachydont
(low-crowned) molariform teeth that are supported by at least two roots, not a single massive root. The direction of wear on the teeth indicates that Ferugliotherium, Gondwanatherium, and Sudamerica all had palinal jaw movement (i.e., the lower jaw moved backwards during the power stroke of chewing)—a feature otherwise only seen in multituberculates among mammals.
only on the lower (ventral) side. A large wear facet is present at the tip, forming an angle of about 35° with the ventral margin in 701A. The three incisor fragments are identified as Ferugliotherium on the basis of size, provenance, and the presence of a restricted enamel band. They show features, such as lateral compression, an acute angle at the tip, small curvature, and an irregular cross section, that are usually seen in lower incisors in mammals with similar, procumbent incisors, such as rodents and taeniolabidoid multituberculates.
Four specimens (MACN Pv-RN 702A through 702D) are thought to represent second upper incisors (I2) of Ferugliotherium. 702A (height 1.5 mm; width 1.1 mm) and 702B are slightly larger than 702C (height 1.2 mm; width 0.9 mm) and 702D. The smaller incisors cannot be lateral incisors (I3), because 702C's wear facet is stronger than would be expected in an I3; therefore, all four upper incisors are identified as central incisors (I2). To explain the size difference, Krause and colleagues suggested that Ferugliotherium was variable in size or that the smaller incisors were deciduous precursors of the larger permanent tooth; they considered it less likely that multiple species with similar incisors were present. The upper incisors have enamel only on the dorsal side. The wear facet at the tip is preserved only in 702C, forming an angle of 52° with the dorsal side, and is more concave than the facet in the lower incisors. 702A–D are recognizable as upper incisors because they are less laterally compressed, more curved, and elliptical in cross section, and have a less acute angle at the tip.
Incisors of Ferugliotherium and Gondwanatherium are similar in overall shape and share a restricted band of enamel—a feature otherwise seen only in multituberculates among Mesozoic mammals. The incisors of Sudamerica are also similar.
(lower jaw) preserving one premolar, was discovered in 1991 and tentatively identified as Ferugliotherium by Kielan-Jaworowska and Bonaparte in 1996, but this assignment remains controversial. The poorly preserved and worn premolar is a bladelike tooth, resembling multituberculate fourth lower premolars (p4). The premolar is 4.8 mm long and bears eight faint ridges on both the labial (towards the lips) and lingual (towards the tongue) sides. On the labial side, the four ridges at the back are more widely separated than the four in front of them. The back and front margins of the tooth are parallel and there is no small cusp on the labial side. There are two roots; the one at the front is larger than the one at the back and bears a furrow. The lower border of the enamel cover is marked by two semicircular extensions of the enamel on the front side, but there is only one such extension at the back. By its size, the number of ridges, and apparently greater length than height, it differs from all known multituberculate first, second, and third lower premolars, indicating that it is a p4.
The dentary itself is robust and short. The length axis of the p4 makes an angle of about 58° with the length axis of the jawbone. The bone is concave on the lingual, but convex on the labial side. There is a diastema
(gap) between the p4 and the incisor which would have been in front of it, as in the jaw of Sudamerica; Gurovich estimated the length of the diastema as 2.5 mm. There is a rounded mental foramen
(an opening in the labial side of the jawbone), with a diameter of 0.7 mm, located about 0.8 mm below the dorsal margin of the bone and 1.5 mm in front of the p4. Although the incisor itself is not preserved, its alveolus (the housing of the root) is in part. As in Sudamerica, it extends far into the dentary, passing below p4. The alveolus is 1.5 mm wide below the front root of p4 and 1.4 mm at the back of the jaw fragment. Although the height of the alveolus cannot be determined because the lower side is broken away, the incisor must have been quite deep.
When it was discovered that Sudamerica had four molariform teeth and no bladelike premolar in its lower jaw, Pascual, Kielan-Jaworowska, and colleagues removed MACN Pv-RN 975 from Ferugliotherium, which they expected to have the same dental formula as its fellow gondwanathere Sudamerica, and identified it as an indeterminate multituberculate instead. Pascual and colleagues argued that molariform teeth as seen in Sudamerica could not have evolved from the bladelike p4 of Ferugliotherium, and that it was unlikely that additional molars had been added in Sudamerica. In 2004 and 2007, Kielan-Jaworowska and colleagues aligned the dentary with the multituberculate suborder "Plagiaulacida
" because the p4 is rectangular in labial view, not curved as in the suborder Cimolodonta
. This feature was also used to distinguish MACN Pv-RN 975 from the single p4 assigned to Argentodites, which was tentatively placed in Cimolodonta.
Gurovich, Guillermo Rougier, and colleagues, on the other hand, maintain that the dentary is referable to Ferugliotherium and that the p4s of Argentodites and MACN Pv-RN 975 are very similar. The alveolus of MACN Pv-RN 975 fits the lower incisors attributed to Ferugliotherium in size and the blade-like premolar is of the size expected for an animal with molariforms the size of Ferugliotherium teeth. If the dentary and premolars (whose identification has been similarly controversial; see below) do not belong to Ferugliotherium, then, Gurovich and Beck argue, the Los Alamitos Formation would contain two mammals (Ferugliotherium and a multituberculate) similar in size and morphology, and therefore presumably occupying similar ecological niche
s—and one of those would be represented only by molariforms and incisors and the other only by premolars and a jaw fragment among the available fossils. Furthermore, they noted that the transition from blade-like to molariform premolars had actually been observed in the fossil record of the extinct sthenurine kangaroos, and that the first molariform in Sudamerica and Gondwanatherium is laterally compressed, suggesting that it may have derived from a blade-like tooth. Gurovich and Beck attributed the difference in shape between the MACN Pv-RN 975 and Argentodites p4s to the extensive wear of the former, and suggested that the two are similar enough that they probably represent at least closely related species.
Bonaparte had identified another tooth, MACN Pv-RN 252, as a possible Ferugliotherium lower premolar in 1990, but this fossil is very fragmentary and according to Krause and colleagues, it cannot even be proven to be a mammalian tooth.
Krause and colleagues identified two teeth, MACN Pv-RN 249 and 250, as anterior upper premolars. 249 bears two longitudinal rows of cusps. One row (row A; possibly the lingual one) includes four cusps, the other (row B) includes at least two, but is damaged. In row A, there are three ridges (at the front, middle, and back) extending from the tip of the base of each cusp. The second and third cusps are largest and most widely separated from each other. In row B, one cusp bears three ridges, of which one extends towards the other cusp in the row and the two others towards row A) and the other cusp is damaged. 250 is more fragmentary, but bears at least five cusps and may represent the same tooth position as 249, though it would come from the opposite side of the mouth. The microstructure of the enamel of this tooth has been studied. With a width of at about 55 μm near the tip of a cusp, the enamel is thin. The enamel prisms are straight, small, and rounded and there is little material between the prisms. Small, rounded prisms are also seen in Gondwanatherium, Sudamerica, and other gondwanatheres, but in few multituberculates. Even in those multituberculates that do have small prisms, the prism sheath is closed, but the sheath is incomplete in Gondwanatherium and possibly Ferugliotherium.
Krause and colleagues wrote that these two teeth resemble multituberculate deciduous anterior upper premolars, particularly second and third premolars (P2 and P3), and used this as one of their arguments for identifying Ferugliotherium as a multituberculate. However, as with the dentary MACN Pv-RN 975, the two upper premolars were excluded from Ferugliotherium and identified as multituberculates by Kielan-Jaworowska and colleagues after the discovery of the jaw of Sudamerica. Gurovich, however, continues to identify them as Ferugliotherium on the basis of their size and provenance and other similarities between Ferugliotherium and multituberculates.
s of Ferugliotherium windhauseni (MACN Pv-RN 20, the only second lower molariform, or m2) and Vucetichia gracilis (MACN Pv-RN 174).
The best-preserved mf1 is MLP 88-III-28-1. The crown is unworn and complete and there are no roots, suggesting that the tooth had not yet erupted when its owner died. Krause, who first described the tooth in 1993, identified it as a right molar, but the subsequent discovery of the jaw of Sudamerica made it clear that Ferugliotherium molariforms had been reversed, and MLP 88-III-28-1 is actually from the left side of the jaw. The tooth is 2.2 mm long and 1.5 mm wide. The crown is about rectangular, with rounded corners, and bears two longitudinal rows of cusps. The lingual row consists of four cusps, which are smaller and lower than the three labial ones. The cusps in this row become smaller and lower from the front to the back. Two ridges descend from the tip of each cusp to the lingual and labial sides. The labial ridges on the first and fourth cusp only reach the base of the cusp, but those on the second and third cusps join ridges descending from the first and second labial cusp. In the first three cusps, the lingual ridge extends to near the lingual margin of the tooth and then turns backward; the end of the ridge is lingual to the next cusp. In the fourth cusp, the ridge hardly extends posteriorly, but rather labially, forming the posterior margin of the tooth and joining a ridge descending from the last labial cusp. The labial cusp row includes three, larger cusps, each of which bears two ridges that descend lingually into the valley between the two cusp rows. The front ridge of each pair ends in the central valley, and the back ridge joins a ridge from a lingual cusp. The ridge pattern results in the presence of three transverse furrows between the main cusps.
Another mf1, MACN Pv-RN 253, is almost unworn, but damaged; only the front two lingual cusps and the first two cusps and part of the third in the labial row are preserved. This tooth is similar to MLP 88-III-28-1 in all respects. However, Gurovich suggests that it may also be an m2. MACN Pv-RN 174, which is heavily worn, and MACN Pv-RN 175, which is not only heavily worn but has also undergone severe abrasion, were originally identified as upper molars of Vucetichia gracilis by Bonaparte in 1990. The roots of MACN Pv-RN 174 are preserved; at the front and back of the tooth, there is a pair of roots, which are fused near their bases. It has small enamel prisms. Krause and colleagues suggested in 1992 that 174 and 175 were mf1s of Ferugliotherium on the basis of similarities with 253, and Krause confirmed this in 1993 by describing the complete mf1 MLP 88-III-28-1. The related ferugliotheriid genus Trapalcotherium is known from a single mf1, which is similar to Ferugliotherium mf1s but different in some morphological details (see Trapalcotherium: Relationships).
The holotype, MACN Pv-RN 20, is a right mf2 according to both Krause and colleagues (1992) and Gurovich (2005), but Gurovich considered the side that Krause and colleagues thought was lingual to be labial, and vice versa; the latter interpretation is used in the following description. It is almost square, but at the front it is slightly narrower than at the back. The labial side of the tooth is taller and less worn than the lingual side. There are two rows of cusps, and each lingual cusp is connected to each labial cusp by a broad loph, with one or more fossas in the middle. One of the two labial cusps may have been divided into two smaller cusps. The two lophs are separated by a deep furrow. The enamel prisms of this tooth are small, like those of the premolar MACN Pv-RN 250.
Transverse ridges between the cusps, as seen in Ferugliotherium, are known in only one multituberculate, Essonodon
, but the ridge pattern in Essonodon is more complicated and the animal lacks the prominent furrows of Ferugliotherium and differs in numerous other features. On the other hand, overall patterns of cusps and ridges are essentially similar among Ferugliotherium, Gondwanatherium, and Sudamerica, indicating that the three are closely related.
, an enigmatic tooth from the Paleogene
of Santa Rosa, Peru, may represent an upper molar of an animal related to Ferugliotherium; it shares anteroposteriorly compressed cusps that are connected to the center of the crown by low crests with Ferugliotherium.
MACN Pv-RN 248 is somewhat damaged and almost rectangular, but slightly narrower at the back than at the front. The tooth bears three longitudinal rows of cusps. The middle row consists of five cusps, the labial row (assuming it is a left M1; if it is from the right, "lingual" and "labial" should be reversed) includes two or perhaps three cusps, and the lingual row includes probably four cusps. The lingual and middle rows extend across the entire length of the tooth, but the labial row is shorter, extending across about 70% of the length. The middle row is oriented oblique with respect to the length axis of the tooth, so that it converges with the lingual row towards the back of the tooth. The front lingual corner of the tooth is missing, but it appears that the first cusps in the lingual and middle rows are connected by two ridges, one at the front margin of the tooth and one at the back of the cusps; a deep fossa (basin) lies between the two cusps and their connecting ridges. Behind these two cusps, a transverse furrow extends across the width of the tooth. The second lingual and middle cusps are also connected by a crest, which is somewhat weaker than those connecting the first cusps. Another transverse furrow extends behind the second cusps and also separates the second middle cusp from the labial row. A third furrow, behind the third lingual and middle cusps, also separates the first from the second labial cusp. Three ridges descend from the fourth lingual cusp: one connects to the fourth middle cusp, one ends blindly between the fourth lingual and middle cusps, and one connects to the fifth middle cusp. The second labial cusp, which is larger than the first one, is superficially divided into two smaller cusps by an indentation on its lingual side. There are vertical grooves at the bases of the cusps.
of southern Argentina, the Los Alamitos
and La Colonia Formation
s. These and the Allen Formation
(which has yielded Trapalcotherium) are all dated to the Campanian
(84–71 million years ago) and/or Maastrichtian
(71–66 million years ago), the penultimate and ultimate stages of the Cretaceous. The La Colonia Formation may be somewhat younger than the other two, and the Los Alamitos Formation has been considered Campanian, and can be dated to the Campanian or Maastrichtian on the basis of palynology
. The Allen Formation is likely Maastrichtian, but not latest Maastrichtian.
The Los Alamitos Formation is located in southeastern Río Negro Province
, in the vicinity of the town of Cona Niyeu
and was probably deposited in a marshy environment. In 1983, it yielded the first Mesozoic mammal to be found in Argentina, Mesungulatum houssayi, and since then, the mammalian fauna has expanded to 14 species. Most of those belong to the archaic mammalian group Dryolestoidea
, but the fauna also includes the gondwanatheres Ferugliotherium and Gondwanatherium, and the unusual possible triconodont Austrotriconodon, The dryolestoids Mesungulum houssayi and Groebertherium novasi and the two gondwanatheres are the most common mammals. Other fossils found in the Los Alamitos Formation include fish, frogs, turtles, madtsoiid
snakes, dinosaurs such as Secernosaurus
, gastropods, and other invertebrates.
The La Colonia Formation outcrops in north-central Chubut Province
, and the mammalian fossils come from the Mirasol Chico valley. The formation includes fluvial (river), deep-sea, and near-shore deposits, and the mammalian fauna probably comes from an estuary, tidal flat, or coastal plain. The La Colonia Formation also contains dryolestoids, such as Coloniatherium
and Reigitherium
, as well as a ferugliotheriid and the putative multituberculate Argentodites. The La Colonia Formation also contains fossils of a wide array of other animals, including crocodiles, plesiosaur
s, lungfish (Ceratodus
), and dinosaurs (including Carnotaurus
).
The high-crowned sudamericids were probably herbivores, but the lower-crowned Ferugliotherium was probably an insectivore or omnivore, like similar multituberculates such as Mesodma
, which is thought to have eaten insects, other arthropods, seeds, and/or nuts. It may have used its incisors for gnawing or slicing, and the blade-like p4 may also have been used for slicing hard plant parts, such as seeds. The wear on Ferugliotherium teeth also suggests that the animal may have eaten some plant material.
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
from the Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
and/or Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
(Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
, around 70 million years ago) of Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
in the family Ferugliotheriidae
Ferugliotheriidae
Ferugliotheriidae is one of two known families in the order Gondwanatheria, an enigmatic group of extinct mammals. Gondwanatheres have been classified as a group of uncertain affinities or as members of Multituberculata, a major extinct mammalian order. The best-known representative of...
. The genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
contains a single species, Ferugliotherium windhauseni, which was first described in 1986. Originally interpreted as a member of the extinct mammalian group Multituberculata
Multituberculata
The Multituberculata were a group of rodent-like mammals that existed for approximately one hundred and twenty million years—the longest fossil history of any mammal lineage—but were eventually outcompeted by rodents, becoming extinct during the early Oligocene. At least 200 species are...
on the basis of a single brachydont
Brachydont
Brachydont is a type of dentition characterized by low-crowned teeth, as opposed to high-crowned, hypsodont teeth. Human teeth are brachydont.-External links:*http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/tooth_diversity.html...
(low-crowned) molar
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
, it was recognized as related to the hypsodont
Hypsodont
Hypsodont dentition is characterized by high-crowned teeth and enamel which extends past the gum line. This provides extra material for wear and tear. Some examples of animals with hypsodont dentition are cows, horses and deer; all animals that feed on gritty, fibrous material. The opposite...
(high-crowned) Sudamericidae
Sudamericidae
Sudamericidae is a family of gondwanathere mammals that lived during the late Cretaceous to Eocene. Its members include Lavanify from the Cretaceous of Madagascar, Bharattherium from the Cretaceous of India, Gondwanatherium from the Cretaceous of Argentina, Sudamerica from the Paleocene of...
after the discovery of additional material in the early 1990s. After the discovery of a jaw of the sudamericid Sudamerica
Sudamerica
Sudamerica, literally "South America" in Spanish, is a genus of mammal from the extinct suborder Gondwanatheria that lived in Patagonia, South America during the Paleocene, just after the end of the "Age of Dinosaurs"....
in 1999, these taxa (collectively known as Gondwanatheria
Gondwanatheria
Gondwanatheria is an extinct group of mammals that lived during the Upper Cretaceous through the Eocene in the Southern Hemisphere, including Antarctica...
) were no longer considered to be multituberculates and a few fossils that were previously considered to be Ferugliotherium were assigned to indeterminate multituberculates instead. Since 2005, a relationship between gondwanatheres and multituberculates has again received support. A closely related animal, Trapalcotherium
Trapalcotherium
Trapalcotherium is a fossil mammal from the Cretaceous of Argentina in the family Ferugliotheriidae. The single species, T. matuastensis, is known from one tooth, a first lower molar. It is from the Allen Formation, which is probably Maastrichtian in age, and was first described in 2009...
, was described in 2009 on the basis of a single tooth.
About twenty teeth and a jaw fragment have been referred to Ferugliotherium, but the assignment of many of these is controversial or has been superseded. The upper and lower incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
s are long and rodent-like and have enamel
Tooth enamel
Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...
on only one side of the crown. A fragment of the lower jaw shows that the tooth socket
Dental alveolus
Dental alveolus are sockets in the jaws in which the roots of teeth are held in the alveolar process of maxilla with the periodontal ligament. The lay term for dental alveoli is tooth sockets...
of the lower incisor was very long, extending below the fourth premolar
Premolar
The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered as a 'transitional tooth' during chewing, or...
(p4). The p4 is preserved in this fragment; it is blade-shaped and resembles multituberculate p4s. However, the determination of this dentary fragment as Ferugliotherium is in question. The identity of a few additional isolated premolars assigned to Ferugliotherium, some also resembling multituberculates, is also uncertain. The first lower molariform (molar-like tooth; mf1) is known from four examples, of which two were originally identified as upper molars of a different species (Vucetichia gracilis), which is now considered a synonym
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
of Ferugliotherium. They bear two longitudinal rows of three or four cusps
Cusp (dentistry)
A cusp is an occlusal or incisal eminence on a tooth.Canine teeth, otherwise known as cuspids, each possess a single cusp, while premolars, otherwise known as bicuspids, possess two each. Molars normally possess either four or five cusps...
and transverse crests and furrows. A single example each of the second lower (mf2) and first upper molariform (MF1) show that these teeth also had longitudinal cusp rows and transverse furrows and crests, but the mf2 had only two or perhaps three cusps per row and the MF1 had three longitudinal rows.
Although Ferugliotherium teeth are much lower-crowned than those of the Sudamericidae, they share an essentially similar pattern on the occlusal (chewing) surface of mf1 and mf2, similar incisors, backward jaw movement during chewing, and enamel with small prisms. Ferugliotherium is thought to have been a small animal, with a body mass of about 70 g (2.5 oz), and may have eaten insects and plant material. Its remains have been found in two formations of southern Argentina, where it is part of a mammal fauna that also includes the sudamericid Gondwanatherium
Gondwanatherium
Gondwanatherium is a genus of mammal from the extinct suborder Gondwanatheria that lived in Patagonia, South America during the "Age of Dinosaurs", specifically the Upper Cretaceous....
, a variety of dryolestoids, and the possible triconodont Austrotriconodon.
Taxonomy
Ferugliotherium windhauseni was named in 1986 by Argentinean paleontologist José BonaparteJosé Bonaparte
José Fernando Bonaparte, Ph.D. , is an Argentine paleontologist who discovered a plethora of South American dinosaurs and mentored a new generation of Argentine paleontologists like Rodolfo Coria...
on the basis of a single second lower molar
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
(m2) from the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
Los Alamitos Formation
Los Alamitos Formation
The Los Alamitos Formation is a geological formation in Rio Negro, Argentina whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.-Dinosaurs:-Mammaliaforms:-References:...
of Argentina. The generic name, Ferugliotherium, honors Italian paleontologist Egidio Feruglio
Egidio Feruglio
Egidio Feruglio was an Italian-born geologist who spent most of his career in Argentina.-Early life:The seventh of twelve sons, Feruglio finished grammar school in 1914, and then enrolled at the University of Florence. In Florence, he studied medicine and natural sciences, graduating in 1920...
. Bonaparte created a new family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
, Ferugliotheriidae
Ferugliotheriidae
Ferugliotheriidae is one of two known families in the order Gondwanatheria, an enigmatic group of extinct mammals. Gondwanatheres have been classified as a group of uncertain affinities or as members of Multituberculata, a major extinct mammalian order. The best-known representative of...
, for the new species and tentatively assigned it to Multituberculata
Multituberculata
The Multituberculata were a group of rodent-like mammals that existed for approximately one hundred and twenty million years—the longest fossil history of any mammal lineage—but were eventually outcompeted by rodents, becoming extinct during the early Oligocene. At least 200 species are...
, a group of mammals that was diverse during the late Cretaceous, mostly in the northern continents (Laurasia
Laurasia
In paleogeography, Laurasia was the northernmost of two supercontinents that formed part of the Pangaea supercontinent from approximately...
), but is now extinct. In subsequent years, other finds permitted a more confident assignment to Multituberculata. In 1990, Bonaparte described Vucetichia gracilis on the basis of what he interpreted as two upper molars of a relative of Gondwanatherium
Gondwanatherium
Gondwanatherium is a genus of mammal from the extinct suborder Gondwanatheria that lived in Patagonia, South America during the "Age of Dinosaurs", specifically the Upper Cretaceous....
within the order Gondwanatheria
Gondwanatheria
Gondwanatheria is an extinct group of mammals that lived during the Upper Cretaceous through the Eocene in the Southern Hemisphere, including Antarctica...
, a small mammalian group that was at the time known only from Argentinean fossils and thought to be related to xenarthra
Xenarthra
The superorder Xenarthra is a group of placental mammals , existent today only in the Americas and represented by anteaters, tree sloths, and armadillos. The origins of the order can be traced back as far as the Paleogene in South America...
ns within a group called Paratheria
Paratheria (mammals)
Paratheria is an obsolete term used for a group that included at least the xenarthran mammals. It was proposed by Oldfield Thomas in 1887 to set apart the sloths, anteaters, armadillos, and pangolins, usually classified as placentals, from both marsupial and placental mammals, an arrangement that...
. The generic name, Vucetichia, honors Argentinean paleontologist Guiomar Vucetich, and the specific name, gracilis (Latin for "slender"), refers to the animal's small size.
However, in 1990 David Krause and Bonaparte argued that Gondwanatheria, including Ferugliotherium (family Ferugliotheriidae), Gondwanatherium, and Sudamerica
Sudamerica
Sudamerica, literally "South America" in Spanish, is a genus of mammal from the extinct suborder Gondwanatheria that lived in Patagonia, South America during the Paleocene, just after the end of the "Age of Dinosaurs"....
(family Sudamericidae
Sudamericidae
Sudamericidae is a family of gondwanathere mammals that lived during the late Cretaceous to Eocene. Its members include Lavanify from the Cretaceous of Madagascar, Bharattherium from the Cretaceous of India, Gondwanatherium from the Cretaceous of Argentina, Sudamerica from the Paleocene of...
), should be placed within Multituberculata. Two years later, Krause, Bonaparte, and Zofia Kielan-Jaworowska
Zofia Kielan-Jaworowska
Zofia Kielan-Jaworowska is a Polish paleobiologist. In the mid-1960s Kielan-Jaworowska led a series of Polish-Mongolian paleontological expeditions to the Gobi Desert...
described additional material of Ferugliotherium (which they tentatively placed in the multituberculate suborder Plagiaulacoidea) and suggested that the supposed upper molars of Vucetichia were in fact heavily worn first lower molariforms (mf1) of Ferugliotherium. In 1993, Krause described an unworn mf1 of Ferugliotherium and confirmed that Vucetichia was based on worn specimens of Ferugliotherium and therefore a synonym
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
of the latter. In the same year, he and Bonaparte argued once again that Ferugliotherium, Gondwanatherium, and Sudamerica formed a closely related group of mulituberculates, which they called the superfamily Gondwanatherioidea. Kielan-Jaworowska and Bonaparte described a lower jaw fragment with a multituberculate-like lower fourth premolar
Premolar
The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered as a 'transitional tooth' during chewing, or...
(p4) from Los Alamitos and tentatively identified it as Ferugliotherium. On the basis of the morphological features of the jaw fragment, they argued that gondwanatherians are not closely related to any other multituberculate group, and consequently placed them in a suborder of their own, Gondwanatheria.
In 1999, Rosendo Pascual and colleagues described a jaw of Sudamerica. Because some of the features of this jaw were thought to be incompatible with a multituberculate identity, they regarded gondwanatheres (including Ferugliotherium) as Mammalia incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
. However, in 2009 Yamila Gurovich and Robin Beck argued in favor of a close relationship between gondwanatheres (including Ferugliotherium) and multituberculates. The controversy is partially due to disagreement over the assignment of two upper premolars and the jaw fragment described by Kielan-Jaworowska and Bonaparte in 1996; Gurovich and Beck identify these as Ferugliotherium, while Kielan-Jaworowska and others regard them as indeterminate multituberculates.
In the 2000s, some possible close relatives of Ferugliotherium were discovered. An enigmatic tooth from the Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...
of Peru, LACM 149371
LACM 149371
LACM 149371 is an enigmatic fossil mammalian tooth from the Paleogene of Peru. It is from the Santa Rosa fossil site, which is of uncertain age but possibly late Eocene or Oligocene...
, was described in 2004 as possibly related to the family Ferugliotheriidae. In 2007, Kielan-Jaworowska and colleagues described a p4 from the La Colonia Formation
La Colonia Formation
The La Colonia Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation....
(Late Cretaceous of Argentina) as a new multituberculate genus, Argentodites
Argentodites
Argentodites is a possible multituberculate mammal from the Cretaceous of Argentina. The single species, Argentodites coloniensis, is known from a single blade-like fourth lower premolar from the La Colonia Formation, which is mostly or entirely Maastrichtian in age...
, but Gurovich and Beck noted close similarities between this p4 and the p4 in the possible jaw fragment of Ferugliotherium and suggested that it represented Ferugliotherium or a closely related species. In 2009, a single mf1 from the Allen Formation
Allen Formation
The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous The Allen Formation is a geological formation in Argentina whose strata date back to the...
(Late Cretaceous of Argentina) was described as another ferugliotheriid genus, Trapalcotherium
Trapalcotherium
Trapalcotherium is a fossil mammal from the Cretaceous of Argentina in the family Ferugliotheriidae. The single species, T. matuastensis, is known from one tooth, a first lower molar. It is from the Allen Formation, which is probably Maastrichtian in age, and was first described in 2009...
.
Description
| Specimen | Organ | Currently identified as Ferugliotherium? | Length (mm) | Width (mm) | Height (mm) |
|---|---|---|---|---|---|
| MACN Pv-RN 20 | Right mf2 | Yes (holotype Holotype A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype... ) |
1.70 | 1.70 | – |
| MACN Pv-RN 174 | Left mf1 | Yes (holotype Holotype A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype... of Vucetichia gracilis) |
2.20 | 1.60 | – |
| MACN Pv-RN 175 | Right mf1 | Yes | 2.10 | 1.40 | |
| MACN Pv-RN 248 | Left MF1 | Yes | 2.50 | 1.70 | – |
| MACN Pv-RN 249 | dP2/dP3? | Possibly | 1.50 | 0.70 | – |
| MACN Pv-RN 250 | dP2/dP3? | Possibly | – | – | – |
| MACN Pv-RN 251 | dp1/dp2/dp3? | Possibly | 0.85 | 0.50 | – |
| MACN Pv-RN 252 | Lower premolar? | Not even certainly mammalian | – | – | – |
| MACN Pv-RN 253 | Right mf1 | Yes | – | 1.50 | – |
| MACN Pv-RN 701A | Left i1 | Yes | – | 1.30 | 2.40 |
| MACN Pv-RN 701B | Left i1 | Yes | – | – | – |
| MACN Pv-RN 701C | Right i1 | Yes | – | – | – |
| MACN Pv-RN 702A | I2 | Yes | – | 1.10 | 1.50 |
| MACN Pv-RN 702B | I2 | Yes | – | – | – |
| MACN Pv-RN 702C | I2 | Yes | – | 0.90 | 1.20 |
| MACN Pv-RN 702D | I2 | Yes | – | – | – |
| MACN Pv-RN 970 (or 254) | Right i1 | No (referred to Gondwanatherium Gondwanatherium Gondwanatherium is a genus of mammal from the extinct suborder Gondwanatheria that lived in Patagonia, South America during the "Age of Dinosaurs", specifically the Upper Cretaceous.... ) |
~40 (broken) | 3.1 | 6.3 |
| MACN Pv-RN 975 | Dentary fragment with p4 | Possibly | 4.8 (p4) | 0.9 (p4) | – |
| MLP 88-III-28-1 | Left mf1 | Yes | 2.2 | 1.5 | – |
Ferugliotherium is known from isolated teeth, the assignment of some of which is controversial. The material from the Los Alamitos Formation, which is mostly in the Museo Argentino de Ciencias Naturales Bernardino Rivadavia (MACN) in Buenos Aires
Buenos Aires
Buenos Aires is the capital and largest city of Argentina, and the second-largest metropolitan area in South America, after São Paulo. It is located on the western shore of the estuary of the Río de la Plata, on the southeastern coast of the South American continent...
, with one tooth in the Museo de La Plata (MLP) in La Plata, Argentina, has been thoroughly described; while there are additional Ferugliotherium fossils from the La Colonia Formation, they have not been described in detail. Although the fragmentary nature of the known fossils of Ferugliotherium makes it impossible to determine its dental formula with certainty, Gurovich suggested that it had one incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
(possibly two in the upper jaw), no canines, one or two premolars, and two molars on each side of the lower and upper jaws. However, on the basis of comparisons with Sudamerica, which is known to have had four lower molariforms (molar-like teeth, either premolars or molars) in its lower jaw, Pascual and Ortiz-Jaureguizar suggested in 2007 that Ferugliotherium may also have had four lower molars.
Ferugliotherium was much smaller than the sudamericids Gondwanatherium and Sudamerica, and its body mass is estimated to have been about 70 g (2.5 oz). Unlike the hypsodont
Hypsodont
Hypsodont dentition is characterized by high-crowned teeth and enamel which extends past the gum line. This provides extra material for wear and tear. Some examples of animals with hypsodont dentition are cows, horses and deer; all animals that feed on gritty, fibrous material. The opposite...
(high-crowned) sudamericids, Ferugliotherium has brachydont
Brachydont
Brachydont is a type of dentition characterized by low-crowned teeth, as opposed to high-crowned, hypsodont teeth. Human teeth are brachydont.-External links:*http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/tooth_diversity.html...
(low-crowned) molariform teeth that are supported by at least two roots, not a single massive root. The direction of wear on the teeth indicates that Ferugliotherium, Gondwanatherium, and Sudamerica all had palinal jaw movement (i.e., the lower jaw moved backwards during the power stroke of chewing)—a feature otherwise only seen in multituberculates among mammals.
Incisors
Three fragmentary Ferugliotherium lower incisors (MACN Pv-RN 701A, 701B, and 701C) are known from the Los Alamitos Formation. Another incisor, MACN Pv-RN 970, was assigned to Ferugliotherium by Bonaparte in 1990, but it is much larger than the other three incisors, which are otherwise similar, and probably represents Gondwanatherium instead. Only the tips of the three incisors are preserved. They are laterally compressed, with an estimated width of 1.3 mm and height of 2.4 mm in 701A. The medial side (towards the middle of the mouth) is flat, but the lateral side (towards the sides) is convex. There is enamelTooth enamel
Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...
only on the lower (ventral) side. A large wear facet is present at the tip, forming an angle of about 35° with the ventral margin in 701A. The three incisor fragments are identified as Ferugliotherium on the basis of size, provenance, and the presence of a restricted enamel band. They show features, such as lateral compression, an acute angle at the tip, small curvature, and an irregular cross section, that are usually seen in lower incisors in mammals with similar, procumbent incisors, such as rodents and taeniolabidoid multituberculates.
Four specimens (MACN Pv-RN 702A through 702D) are thought to represent second upper incisors (I2) of Ferugliotherium. 702A (height 1.5 mm; width 1.1 mm) and 702B are slightly larger than 702C (height 1.2 mm; width 0.9 mm) and 702D. The smaller incisors cannot be lateral incisors (I3), because 702C's wear facet is stronger than would be expected in an I3; therefore, all four upper incisors are identified as central incisors (I2). To explain the size difference, Krause and colleagues suggested that Ferugliotherium was variable in size or that the smaller incisors were deciduous precursors of the larger permanent tooth; they considered it less likely that multiple species with similar incisors were present. The upper incisors have enamel only on the dorsal side. The wear facet at the tip is preserved only in 702C, forming an angle of 52° with the dorsal side, and is more concave than the facet in the lower incisors. 702A–D are recognizable as upper incisors because they are less laterally compressed, more curved, and elliptical in cross section, and have a less acute angle at the tip.
Incisors of Ferugliotherium and Gondwanatherium are similar in overall shape and share a restricted band of enamel—a feature otherwise seen only in multituberculates among Mesozoic mammals. The incisors of Sudamerica are also similar.
Mandible with lower premolar
MACN Pv-RN 975, a fragment of the mandibleMandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
(lower jaw) preserving one premolar, was discovered in 1991 and tentatively identified as Ferugliotherium by Kielan-Jaworowska and Bonaparte in 1996, but this assignment remains controversial. The poorly preserved and worn premolar is a bladelike tooth, resembling multituberculate fourth lower premolars (p4). The premolar is 4.8 mm long and bears eight faint ridges on both the labial (towards the lips) and lingual (towards the tongue) sides. On the labial side, the four ridges at the back are more widely separated than the four in front of them. The back and front margins of the tooth are parallel and there is no small cusp on the labial side. There are two roots; the one at the front is larger than the one at the back and bears a furrow. The lower border of the enamel cover is marked by two semicircular extensions of the enamel on the front side, but there is only one such extension at the back. By its size, the number of ridges, and apparently greater length than height, it differs from all known multituberculate first, second, and third lower premolars, indicating that it is a p4.
The dentary itself is robust and short. The length axis of the p4 makes an angle of about 58° with the length axis of the jawbone. The bone is concave on the lingual, but convex on the labial side. There is a diastema
Diastema (dentistry)
Diastema is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars.-In humans:...
(gap) between the p4 and the incisor which would have been in front of it, as in the jaw of Sudamerica; Gurovich estimated the length of the diastema as 2.5 mm. There is a rounded mental foramen
Mental foramen
The mental foramen is one of two holes located on the anterior surface of the mandible. It permits passage of the mental nerve and vessels. The mental foramen descends slightly in edentulous individuals.- Variations :...
(an opening in the labial side of the jawbone), with a diameter of 0.7 mm, located about 0.8 mm below the dorsal margin of the bone and 1.5 mm in front of the p4. Although the incisor itself is not preserved, its alveolus (the housing of the root) is in part. As in Sudamerica, it extends far into the dentary, passing below p4. The alveolus is 1.5 mm wide below the front root of p4 and 1.4 mm at the back of the jaw fragment. Although the height of the alveolus cannot be determined because the lower side is broken away, the incisor must have been quite deep.
When it was discovered that Sudamerica had four molariform teeth and no bladelike premolar in its lower jaw, Pascual, Kielan-Jaworowska, and colleagues removed MACN Pv-RN 975 from Ferugliotherium, which they expected to have the same dental formula as its fellow gondwanathere Sudamerica, and identified it as an indeterminate multituberculate instead. Pascual and colleagues argued that molariform teeth as seen in Sudamerica could not have evolved from the bladelike p4 of Ferugliotherium, and that it was unlikely that additional molars had been added in Sudamerica. In 2004 and 2007, Kielan-Jaworowska and colleagues aligned the dentary with the multituberculate suborder "Plagiaulacida
Plagiaulacida
Plagiaulacida is a group of extinct multituberculate mammals. Multituberculates were among the most common mammals of the Mesozoic, "the age of the dinosaurs"...
" because the p4 is rectangular in labial view, not curved as in the suborder Cimolodonta
Cimolodonta
The Cimolodonta are a taxon of extinct mammals that lived from the Cretaceous to the Eocene. They were some of the more derived members of the extinct order Multituberculata. They probably lived something of a rodent-like existence until their ecological niche was assumed by true rodents...
. This feature was also used to distinguish MACN Pv-RN 975 from the single p4 assigned to Argentodites, which was tentatively placed in Cimolodonta.
Gurovich, Guillermo Rougier, and colleagues, on the other hand, maintain that the dentary is referable to Ferugliotherium and that the p4s of Argentodites and MACN Pv-RN 975 are very similar. The alveolus of MACN Pv-RN 975 fits the lower incisors attributed to Ferugliotherium in size and the blade-like premolar is of the size expected for an animal with molariforms the size of Ferugliotherium teeth. If the dentary and premolars (whose identification has been similarly controversial; see below) do not belong to Ferugliotherium, then, Gurovich and Beck argue, the Los Alamitos Formation would contain two mammals (Ferugliotherium and a multituberculate) similar in size and morphology, and therefore presumably occupying similar ecological niche
Ecological niche
In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...
s—and one of those would be represented only by molariforms and incisors and the other only by premolars and a jaw fragment among the available fossils. Furthermore, they noted that the transition from blade-like to molariform premolars had actually been observed in the fossil record of the extinct sthenurine kangaroos, and that the first molariform in Sudamerica and Gondwanatherium is laterally compressed, suggesting that it may have derived from a blade-like tooth. Gurovich and Beck attributed the difference in shape between the MACN Pv-RN 975 and Argentodites p4s to the extensive wear of the former, and suggested that the two are similar enough that they probably represent at least closely related species.
Other premolars
Krause and colleagues identified a single tooth, MACN Pv-RN 251, as a possible deciduous anterior (i.e., not p4 or dp4, the deciduous version of p4) lower premolar of Ferugliotherium. It is minuscule, with a length of 0.85 mm and width of 0.5 mm (assuming the tooth is oriented correctly). It bears two serrations (small projections) at the tip of the crown—one around the middle of the crown and the other at what may be the back of the crown, where it is highest. Two prominent ridges descend from each serration towards the front down the sides of the tooth. No roots are preserved, but the rounded surface of the lower side of the tooth suggests they may have been resorbed, which would indicate that the tooth is deciduous. Krause and colleauges suggested that the tooth may have been the frontmost premolar, whether deciduous or permanent. However, Kielan-Jaworowska and Bonaparte wrote that this tooth does not match the partial jaw MACN Pv-RN 975, which has no alveoli in front of p4, and Pascual and colleagues agreed in 1999 that the tooth probably does not belong to Ferugliotherium.Bonaparte had identified another tooth, MACN Pv-RN 252, as a possible Ferugliotherium lower premolar in 1990, but this fossil is very fragmentary and according to Krause and colleagues, it cannot even be proven to be a mammalian tooth.
Krause and colleagues identified two teeth, MACN Pv-RN 249 and 250, as anterior upper premolars. 249 bears two longitudinal rows of cusps. One row (row A; possibly the lingual one) includes four cusps, the other (row B) includes at least two, but is damaged. In row A, there are three ridges (at the front, middle, and back) extending from the tip of the base of each cusp. The second and third cusps are largest and most widely separated from each other. In row B, one cusp bears three ridges, of which one extends towards the other cusp in the row and the two others towards row A) and the other cusp is damaged. 250 is more fragmentary, but bears at least five cusps and may represent the same tooth position as 249, though it would come from the opposite side of the mouth. The microstructure of the enamel of this tooth has been studied. With a width of at about 55 μm near the tip of a cusp, the enamel is thin. The enamel prisms are straight, small, and rounded and there is little material between the prisms. Small, rounded prisms are also seen in Gondwanatherium, Sudamerica, and other gondwanatheres, but in few multituberculates. Even in those multituberculates that do have small prisms, the prism sheath is closed, but the sheath is incomplete in Gondwanatherium and possibly Ferugliotherium.
Krause and colleagues wrote that these two teeth resemble multituberculate deciduous anterior upper premolars, particularly second and third premolars (P2 and P3), and used this as one of their arguments for identifying Ferugliotherium as a multituberculate. However, as with the dentary MACN Pv-RN 975, the two upper premolars were excluded from Ferugliotherium and identified as multituberculates by Kielan-Jaworowska and colleagues after the discovery of the jaw of Sudamerica. Gurovich, however, continues to identify them as Ferugliotherium on the basis of their size and provenance and other similarities between Ferugliotherium and multituberculates.
Lower molariforms
Five putative lower molariforms of Ferugliotherium are known from the Los Alamitos Formation (MACN Pv-RN 20, 174, 175, and 253 and MLP 88-III-28-1). These teeth include the holotypeHolotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
s of Ferugliotherium windhauseni (MACN Pv-RN 20, the only second lower molariform, or m2) and Vucetichia gracilis (MACN Pv-RN 174).
The best-preserved mf1 is MLP 88-III-28-1. The crown is unworn and complete and there are no roots, suggesting that the tooth had not yet erupted when its owner died. Krause, who first described the tooth in 1993, identified it as a right molar, but the subsequent discovery of the jaw of Sudamerica made it clear that Ferugliotherium molariforms had been reversed, and MLP 88-III-28-1 is actually from the left side of the jaw. The tooth is 2.2 mm long and 1.5 mm wide. The crown is about rectangular, with rounded corners, and bears two longitudinal rows of cusps. The lingual row consists of four cusps, which are smaller and lower than the three labial ones. The cusps in this row become smaller and lower from the front to the back. Two ridges descend from the tip of each cusp to the lingual and labial sides. The labial ridges on the first and fourth cusp only reach the base of the cusp, but those on the second and third cusps join ridges descending from the first and second labial cusp. In the first three cusps, the lingual ridge extends to near the lingual margin of the tooth and then turns backward; the end of the ridge is lingual to the next cusp. In the fourth cusp, the ridge hardly extends posteriorly, but rather labially, forming the posterior margin of the tooth and joining a ridge descending from the last labial cusp. The labial cusp row includes three, larger cusps, each of which bears two ridges that descend lingually into the valley between the two cusp rows. The front ridge of each pair ends in the central valley, and the back ridge joins a ridge from a lingual cusp. The ridge pattern results in the presence of three transverse furrows between the main cusps.
Another mf1, MACN Pv-RN 253, is almost unworn, but damaged; only the front two lingual cusps and the first two cusps and part of the third in the labial row are preserved. This tooth is similar to MLP 88-III-28-1 in all respects. However, Gurovich suggests that it may also be an m2. MACN Pv-RN 174, which is heavily worn, and MACN Pv-RN 175, which is not only heavily worn but has also undergone severe abrasion, were originally identified as upper molars of Vucetichia gracilis by Bonaparte in 1990. The roots of MACN Pv-RN 174 are preserved; at the front and back of the tooth, there is a pair of roots, which are fused near their bases. It has small enamel prisms. Krause and colleagues suggested in 1992 that 174 and 175 were mf1s of Ferugliotherium on the basis of similarities with 253, and Krause confirmed this in 1993 by describing the complete mf1 MLP 88-III-28-1. The related ferugliotheriid genus Trapalcotherium is known from a single mf1, which is similar to Ferugliotherium mf1s but different in some morphological details (see Trapalcotherium: Relationships).
The holotype, MACN Pv-RN 20, is a right mf2 according to both Krause and colleagues (1992) and Gurovich (2005), but Gurovich considered the side that Krause and colleagues thought was lingual to be labial, and vice versa; the latter interpretation is used in the following description. It is almost square, but at the front it is slightly narrower than at the back. The labial side of the tooth is taller and less worn than the lingual side. There are two rows of cusps, and each lingual cusp is connected to each labial cusp by a broad loph, with one or more fossas in the middle. One of the two labial cusps may have been divided into two smaller cusps. The two lophs are separated by a deep furrow. The enamel prisms of this tooth are small, like those of the premolar MACN Pv-RN 250.
Transverse ridges between the cusps, as seen in Ferugliotherium, are known in only one multituberculate, Essonodon
Essonodon
Essonodon is a mammal genus from the Upper Cretaceous of North America. It was a member of the extinct order Multituberculata and lived towards the end of the "age of the dinosaurs." It is within the suborder Cimolodonta and perhaps the family Cimolomyidae.The genus Essonodon was named by Simpson...
, but the ridge pattern in Essonodon is more complicated and the animal lacks the prominent furrows of Ferugliotherium and differs in numerous other features. On the other hand, overall patterns of cusps and ridges are essentially similar among Ferugliotherium, Gondwanatherium, and Sudamerica, indicating that the three are closely related.
Upper molariforms
A single tooth, MACN Pv-RN 248, is currently identified as a Ferugliotherium upper molariform. In 1992, Krause and colleagues labeled it as a right MF1, but Gurovich identifies it as a left MF1 or possibly even a right mf1. LACM 149371LACM 149371
LACM 149371 is an enigmatic fossil mammalian tooth from the Paleogene of Peru. It is from the Santa Rosa fossil site, which is of uncertain age but possibly late Eocene or Oligocene...
, an enigmatic tooth from the Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...
of Santa Rosa, Peru, may represent an upper molar of an animal related to Ferugliotherium; it shares anteroposteriorly compressed cusps that are connected to the center of the crown by low crests with Ferugliotherium.
MACN Pv-RN 248 is somewhat damaged and almost rectangular, but slightly narrower at the back than at the front. The tooth bears three longitudinal rows of cusps. The middle row consists of five cusps, the labial row (assuming it is a left M1; if it is from the right, "lingual" and "labial" should be reversed) includes two or perhaps three cusps, and the lingual row includes probably four cusps. The lingual and middle rows extend across the entire length of the tooth, but the labial row is shorter, extending across about 70% of the length. The middle row is oriented oblique with respect to the length axis of the tooth, so that it converges with the lingual row towards the back of the tooth. The front lingual corner of the tooth is missing, but it appears that the first cusps in the lingual and middle rows are connected by two ridges, one at the front margin of the tooth and one at the back of the cusps; a deep fossa (basin) lies between the two cusps and their connecting ridges. Behind these two cusps, a transverse furrow extends across the width of the tooth. The second lingual and middle cusps are also connected by a crest, which is somewhat weaker than those connecting the first cusps. Another transverse furrow extends behind the second cusps and also separates the second middle cusp from the labial row. A third furrow, behind the third lingual and middle cusps, also separates the first from the second labial cusp. Three ridges descend from the fourth lingual cusp: one connects to the fourth middle cusp, one ends blindly between the fourth lingual and middle cusps, and one connects to the fifth middle cusp. The second labial cusp, which is larger than the first one, is superficially divided into two smaller cusps by an indentation on its lingual side. There are vertical grooves at the bases of the cusps.
Range and ecology
Remains of Ferugliotherium come from two formations in the Late CretaceousLate Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
of southern Argentina, the Los Alamitos
Los Alamitos Formation
The Los Alamitos Formation is a geological formation in Rio Negro, Argentina whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.-Dinosaurs:-Mammaliaforms:-References:...
and La Colonia Formation
La Colonia Formation
The La Colonia Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation....
s. These and the Allen Formation
Allen Formation
The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous The Allen Formation is a geological formation in Argentina whose strata date back to the...
(which has yielded Trapalcotherium) are all dated to the Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
(84–71 million years ago) and/or Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
(71–66 million years ago), the penultimate and ultimate stages of the Cretaceous. The La Colonia Formation may be somewhat younger than the other two, and the Los Alamitos Formation has been considered Campanian, and can be dated to the Campanian or Maastrichtian on the basis of palynology
Palynology
Palynology is the science that studies contemporary and fossil palynomorphs, including pollen, spores, orbicules, dinoflagellate cysts, acritarchs, chitinozoans and scolecodonts, together with particulate organic matter and kerogen found in sedimentary rocks and sediments...
. The Allen Formation is likely Maastrichtian, but not latest Maastrichtian.
The Los Alamitos Formation is located in southeastern Río Negro Province
Río Negro Province
Río Negro is a province of Argentina, located at the northern edge of Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean.Its capital is Viedma...
, in the vicinity of the town of Cona Niyeu
Cona Niyeu
Cona Niyeu is a village and municipality in Río Negro Province in Argentina.-References:...
and was probably deposited in a marshy environment. In 1983, it yielded the first Mesozoic mammal to be found in Argentina, Mesungulatum houssayi, and since then, the mammalian fauna has expanded to 14 species. Most of those belong to the archaic mammalian group Dryolestoidea
Dryolestoidea
Dryolestoidea is an extinct clade of Mesozoic mammals that only contains two orders. It has been suggested that this group contained the ancestors of modern therian mammals. They are mostly represented by teeth, fragmented dentaries and parts of the rostrum. The Jurassic forms retained a...
, but the fauna also includes the gondwanatheres Ferugliotherium and Gondwanatherium, and the unusual possible triconodont Austrotriconodon, The dryolestoids Mesungulum houssayi and Groebertherium novasi and the two gondwanatheres are the most common mammals. Other fossils found in the Los Alamitos Formation include fish, frogs, turtles, madtsoiid
Madtsoiidae
Madtsoiidae are an extinct group of mostly Gondwanan snakes with a fossil record extending from early Cenomanian to late Pleistocene strata located in South America, Africa, India, Australia and Southern Europe...
snakes, dinosaurs such as Secernosaurus
Secernosaurus
Secernosaurus is a genus of herbivorous dinosaur. Secernosaurus was a hadrosaur, a "duck-billed" dinosaur which lived during the Late Cretaceous. Its fossils have been found in Argentina....
, gastropods, and other invertebrates.
The La Colonia Formation outcrops in north-central Chubut Province
Chubut Province
Chubut a province in the southern part of Argentina situated between the 42nd parallel south and the 46th parallel south , the Andes range separating Argentina from Chile, and the Atlantic ocean...
, and the mammalian fossils come from the Mirasol Chico valley. The formation includes fluvial (river), deep-sea, and near-shore deposits, and the mammalian fauna probably comes from an estuary, tidal flat, or coastal plain. The La Colonia Formation also contains dryolestoids, such as Coloniatherium
Coloniatherium
Coloniatherium is a dryolestoid mammal from the Late Cretaceous of Argentina. The single species, Coloniatherium cilinskii, was a large member of the family Mesungulatidae.-Taxonomy:...
and Reigitherium
Reigitherium
Reigitherium bunodontum is a mammal that lived during the Late Cretaceous . Fossils of it have been found in the Los Alamitos and the La Colonia Formations of Argentina....
, as well as a ferugliotheriid and the putative multituberculate Argentodites. The La Colonia Formation also contains fossils of a wide array of other animals, including crocodiles, plesiosaur
Plesiosaur
Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...
s, lungfish (Ceratodus
Ceratodus
Ceratodus was a wide-ranging genus of extinct sarcopterygiian lungfish. Fossil evidence dates back to the Middle Triassic 228 million years ago. A wide range of fossil species from different time periods have been found around the world in places such as the United States, Argentina, England,...
), and dinosaurs (including Carnotaurus
Carnotaurus
Carnotaurus was a large predatory dinosaur. Only one species, Carnotaurus sastrei has been described so far.Carnotaurus lived in Patagonia, Argentina during the Campanian or Maastrichtian stage of the Late Cretaceous...
).
The high-crowned sudamericids were probably herbivores, but the lower-crowned Ferugliotherium was probably an insectivore or omnivore, like similar multituberculates such as Mesodma
Mesodma
Mesodma is an extinct genus of mammal, a member of the extinct order Multituberculata within the suborder Cimolodonta, family Neoplagiaulacidae. It lived during the upper Cretaceous and Paleocene Periods of what is now North America...
, which is thought to have eaten insects, other arthropods, seeds, and/or nuts. It may have used its incisors for gnawing or slicing, and the blade-like p4 may also have been used for slicing hard plant parts, such as seeds. The wear on Ferugliotherium teeth also suggests that the animal may have eaten some plant material.