Ferugliotheriidae
Encyclopedia
Ferugliotheriidae is one of two known families
in the order
Gondwanatheria
, an enigmatic group of extinct mammal
s. 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 Ferugliotheriidae is the genus
Ferugliotherium
from the Late Cretaceous
epoch in Argentina
. A second genus, Trapalcotherium
, is known from a single tooth, a first lower molariform (molar-like tooth), from a different Late Cretaceous Argentinean locality. Another genus known from a single tooth (in this case, a fourth lower premolar
), Argentodites
, was first described as an unrelated multituberculate, but later identified as possibly related to Ferugliotherium. Finally, a single tooth from the Paleogene
of Peru
, LACM 149371
, perhaps a last upper molariform, may represent a related animal.
Ferugliotheriids are known from isolated, low-crowned (brachydont
) teeth and possibly a fragment of a lower jaw. Ferugliotherium is estimated to have weighed 70 g (2.5 oz). The incisor
s are long and procumbent and contain a band of enamel
on only part of the tooth. The jaw fragment contains a long tooth socket for the incisor and bears a bladelike fourth lower premolar, resembling those of multituberculates. The premolar of Argentodites is similar. Two upper premolars also resemble multituberculate teeth, but whether these premolars are referable to Ferugliotheriidae is controversial. Molariforms are rectangular and brachydont and consist of longitudinal rows of cusps
, connected by transverse crests and separated by transverse furrows. Lower molariforms have two cusp rows, and the single known putative upper molariform has three. Low-crowned and bladelike teeth as seen in ferugliotheriids may have been evolutionary precursors of the high-crowned (hypsodont
) teeth of the other gondwanathere family, Sudamericidae
.
Most ferugliotheriids come from the Late Cretaceous epoch (Campanian
–Maastrichtian
ages, 84–66 million years ago, or mya) of Argentina, where they may have lived in a marshy or seashore environment. They coexisted with mammals such as dryolestoids and a variety of other animals, including dinosaurs. Ferugliotheriids may have been herbivore
s or omnivore
s.
Los Alamitos Formation
of Argentina. Bonaparte placed Ferugliotherium as the only member of the new family Ferugliotheriidae, which he tentatively assigned to the order Multituberculata
, a large group of extinct mammals (distinct from both monotreme
s and theria
ns, the two major groups of living mammals) that was particularly widespread in the northern continents (Laurasia
), but had never previously been found in the south (Gondwana
). In 1990, Bonaparte named another species, Vucetichia gracilis, from Los Alamitos. He placed it in the family Gondwanatheriidae, together with Gondwanatherium
, another Los Alamitos mammal, within the order Gondwanatheria
, which also contained the family Sudamericidae
, then with the single genus Sudamerica
. Bonaparte considered the gondwanatheres to be probably most closely related to the xenarthra
ns (sloths, armadillos, and anteaters) within a group called Paratheria
.
Also in 1990, Bonaparte merged the family Gondwanatheriidae into Sudamericidae and, together with David Krause, redefined Gondwanatheria as a multituberculate suborder that included both Ferugliotheriidae and Sudamericidae, thus rejecting a relationship between gondwanatheres and xenarthrans. Krause, Bonaparte, and Zofia Kielan-Jaworowska
redescribed Ferugliotherium in 1992 and suggested that the teeth that Vucetichia was based on may have been worn specimens of Ferugliotherium. They placed Ferugliotherium among multituberculates and suggested that it may be part of the suborder Plagiaulacoidea. The following year, Krause confirmed that Vucetichia gracilis is a synonym
of Ferugliotherium windhauseni. Together with Bonaparte, he also proposed to classify gondwanatheres as a superfamily (Gondwanatherioidea) within Plagiaulacoidea, including the families Ferugliotheriidae and Sudamericidae. In 1996, Kielan-Jaworowska and Bonaparte tentatively identified a lower jaw fragment with a multituberculate-like fourth lower premolar
(p4) from Los Alamitos as Ferugliotherium. On the basis of the morphological features of the jaw fragment, they argued that gondwanatheres 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 lower jaw of Sudamerica, which had previously only been known from isolated teeth. This jaw fragment showed that Sudamerica had four molariform (molar
-like teeth) on each side of the lower jaws, more than any multituberculate, and consequently they removed gondwanatheres from Multituberculata and regarded their affinities as uncertain. As a consequence, Kielan-Jaworowska and colleagues excluded Gondwanatheria from multituberculates, but identified the jaw fragment and a few upper premolars of Ferugliotherium as indeterminate multituberculates in a 2001 paper and a 2004 book. However, in 2009 Yamila Gurovich and Robin Beck identified these fossils as Ferugliotherium and argued in favor of a close relationship between gondwanatheres (including Ferugliotheriidae) and multituberculates.
In the 2000s, additional members of Ferugliotheriidae were described. In 2004, Francisco Goin and colleagues described a single enigmatic tooth from the Paleogene
of Peru, LACM 149371
; their best estimate was that it represented a member of Ferugliotheriidae. On the basis of a single p4, Kielan-Jaworowska and colleagues named Argentodites coloniensis, from the Late Cretaceous La Colonia Formation
of Argentina, in 2007 as a multituberculate, possibly referable to the suborder Cimolodonta
. However, Gurovich and Beck argued that the p4 of Argentodites did not differ materially from that in the jaw they allocated to Ferugliotherium, and that Argentodites was based on a specimen of either Ferugliotherium or a closely related animal. Guillermo Rougier and colleagues described mammals from the Allen Formation
, a third Argentinean formation of similar age, in 2009, including a new ferugliotheriid, Trapalcotherium matuastensis. They also regarded Argentodites as a likely relative of Ferugliotherium and suggested that Ferugliotheriidae are either multituberculates or closely related to them.
s, premolars, and molariform teeth have been identified. Gurovich suggested that Ferugliotherium 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.
Unlike the very high-crowned (hypsodont
) sudamericids, ferugliotheriid teeth were low-crowned (brachydont
). Furthermore, sudamericid molariforms tend to be larger and are supported by one large root, but the smaller ferugliotheriids have at least two roots under their molariforms. Ferugliotherium is estimated to have weighed 70 g (2.5 oz).
The incisors, known only from Ferugliotherium, are procumbent and long. Three lower and four upper incisors are known. As is usual in mammals with similarly shaped (gliriform) incisors, the lower incisors are more laterally compressed, are less curved, form a greater angle between the front side and the wear facet at the tip, and are less elliptical in shape than the uppers. The enamel band is restricted to the side that faces the lips in both the lower and upper incisors (the lower side in the lowers and the upper side in the uppers).
The specimen MACN Pv-RN 975, first described by Kielan-Jaworowska and Bonaparte in 1996, may be a jaw fragment of Ferugliotherium, although it has also been identified as an unrelated multituberculate. The fossil preserves a bladelike premolar, identified as the fourth premolar, and the piece of the jawbone below it. A diastema
(gap) is present between the premolar and the incisor that would have been located in front of it. The alveolus
(socket) of the lower incisor extends all the way through the fossil. The p4 bears eight ridges on both sides of the longitudinal crest and is supported by two roots at the front and back. The p4 assigned to Argentodites also has eight ridges on both sides, which descend from cusps
on the upper margin, and roots at the front and back. According to Kielan-Jaworowska and colleagues, it differs from that of MACN Pv-RN 975 in its rounded, as opposed to angular shape. However, Gurovich and Beck attribute this difference to the fact that the latter has undergone much more wear.
Two fossils have been interpreted as isolated lower premolars of Ferugliotherium; however, neither is still regarded as such. Two other teeth have been identified as upper premolars of Ferugliotherium; as with the jaw fragment, they may also represent an indeterminate multituberculate. One of the two preserves two longitudinal rows of cusps, of which one contains four and the other at least two cusps. The other is more poorly preserved, but may represent the same tooth position. These teeth resemble multituberculate upper premolars.
Four putative first lower molariforms (mf1s) of Ferugliotherium are known, and the only known tooth of Trapalcotherium is also thought to be an mf1. Ferugliotherium mf1s are roughly rectangular, with rounded corners, and bear two longitudinal rows of cusps. There are four cusps in the lingual row (on the side of the tongue) and three in the labial row (the side of the lips). The cusps are connected to cusps in the other row by transverse ridges and separated from cusps in their own rows by three transverse furrows. Two heavily worn Ferugliotherium mf1s were originally identified as upper molars of Vucetichia gracilis by Bonaparte in 1990. One of the two preserves the roots; at the front and back, there were two roots, fused at their bases. The mf1 of Trapalcotherium differs only in some details; among others, the cusps are less distinct from the crests. The sole mf2 of Ferugliotherium is the holotype
. It bears two rows of two cusps. The cusps in the front and back pairs are connected by a broad ridge and the two pairs are separated by a deep furrow. Transverse ridges between the cusps similar to those seen in ferugliotheriids are not known in any multituberculate. 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.
One Ferugliotherium tooth is thought to be a first upper molariform (MF1). It is almost rectangular and bears three longitudinal rows of cusps. There are five cusps in the middle row, which is oriented obliquely, four cusps in one of the rows on the side of the tooth, and two or three in the other row on the side. As in the lower molariforms, the cusps are connected by transverse ridges and separated by furrows. LACM 149371, the enigmatic possibly ferugliotheriid tooth from Peru, is a triangular tooth bearing six or seven cusps, which are connected by crests and surround two deep fossae (basins) and a third shallower fossa.
, which is thought to have eaten insects, other arthropods, seeds, and/or nuts. The wear on Ferugliotherium teeth suggests that the animal may have eaten some plant material. The high-crowned sudamericids are thought to have been herbivores feeding on abrasive vegetation, although their precise diet is not known. In the evolutionary history of gondwanatheres, hypsodont teeth are thought to have evolved from brachydont precursors. Gurovich hypothesizes that the anterior molariforms of sudamericids may have evolved from bladelike premolars as seen in Ferugliotherium.
Fossils of Argentinean ferugliotheriids come from the Los Alamitos
(Ferugliotherium), La Colonia
(Ferugliotherium and Argentodites), and Allen Formation
s (Trapalcotherium). All three are approximately the same age, dating to the Campanian
(84–71 mya) or more likely the Maastrichtian
(71–66 mya), but the La Colonia Formation is perhaps a little younger. The Los Alamitos and Allen Formations may have been deposited in a marshy environments, and the depositional environment of the La Colonia Formations may have been an estuary
, tidal flat, or coastal plain
.
In each of the three formations, the mammalian fauna is dominated by the archaic group Dryolestoidea
; the Los Alamitos Formation has also produced the sudamericid Gondwanatherium and the possible triconodont Austroconodon. However, only seven mammalian teeth have been found in the Allen Formation. All three also contain remains of numerous other animals, including dinosaurs, amphibians, and fish.
The Santa Rosa fossil site, where LACM 149371 was found, is in the Ucayali Region
of Peru. The Santa Rosa fauna also contains fossils of various unique species of marsupial
s and hystricognath rodents, a possible bat, and some notoungulates (a unique extinct group of South American ungulates). The age of this fauna is unclear, and estimates range from near the Eocene
–Oligocene
boundary (~35 mya) to the late Oligocene (~25 mya). The Santa Rosa mammals may have lived in a savanna
habitat that contained rivers.
The range of the Ferugliotheriidae is narrower than that of Sudamericidae; sudamericids have been recorded from the Late Cretaceous (Gondwanatherium) and Paleocene
(Sudamerica) of Argentina, the Late Cretaceous of Madagascar (Lavanify
) and India (Bharattherium
), the Middle Eocene of Antarctica (probably Sudamerica), and perhaps the Cretaceous of Tanzania (TNM 02067
, tentatively referred to Sudamericidae). Nevertheless, if LACM 149371 is a ferugliotheriid, it would likely represent the youngest record of gondwanatheres.
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...
in the order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Gondwanatheria
Gondwanatheria
Gondwanatheria is an extinct group of mammals that lived during the Upper Cretaceous through the Eocene in the Southern Hemisphere, including Antarctica...
, an enigmatic group of extinct mammal
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...
s. Gondwanatheres have been classified as a group of uncertain affinities or as members of 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 major extinct mammalian order. The best-known representative of Ferugliotheriidae is 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...
Ferugliotherium
Ferugliotherium
Ferugliotherium is a fossil mammal from the Campanian and/or Maastrichtian of Argentina in the family Ferugliotheriidae. The genus contains a single species, Ferugliotherium windhauseni, which was first described in 1986...
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...
epoch in 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...
. A second 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...
, is known from a single tooth, a first lower molariform (molar-like tooth), from a different Late Cretaceous Argentinean locality. Another genus known from a single tooth (in this case, a fourth lower 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...
), 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...
, was first described as an unrelated multituberculate, but later identified as possibly related to Ferugliotherium. Finally, a single 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
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
, 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...
, perhaps a last upper molariform, may represent a related animal.
Ferugliotheriids are known from isolated, low-crowned (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...
) teeth and possibly a fragment of a lower jaw. Ferugliotherium is estimated to have weighed 70 g (2.5 oz). The 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 procumbent and contain a band of 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 part of the tooth. The jaw fragment contains a long tooth socket for the incisor and bears a bladelike fourth lower premolar, resembling those of multituberculates. The premolar of Argentodites is similar. Two upper premolars also resemble multituberculate teeth, but whether these premolars are referable to Ferugliotheriidae is controversial. Molariforms are rectangular and brachydont and consist of longitudinal rows of 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...
, connected by transverse crests and separated by transverse furrows. Lower molariforms have two cusp rows, and the single known putative upper molariform has three. Low-crowned and bladelike teeth as seen in ferugliotheriids may have been evolutionary precursors of the high-crowned (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...
) teeth of the other gondwanathere 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...
.
Most ferugliotheriids come from the Late Cretaceous epoch (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 ...
–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...
ages, 84–66 million years ago, or mya) of Argentina, where they may have lived in a marshy or seashore environment. They coexisted with mammals such as dryolestoids and a variety of other animals, including dinosaurs. Ferugliotheriids may have been herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s or omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...
s.
Taxonomy
The first member of the family Ferugliotheriidae to be discovered, Ferugliotherium windhauseni, was named in 1986 by Argentinean paleontologist José F. Bonaparte on the basis of a tooth from 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...
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. Bonaparte placed Ferugliotherium as the only member of the new family Ferugliotheriidae, which he tentatively assigned to the order 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 large group of extinct mammals (distinct from both monotreme
Monotreme
Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals...
s and theria
Theria
Theria is a subclass of mammals that give birth to live young without using a shelled egg, including both eutherians and metatherians . The only omitted extant mammal group is the egg-laying monotremes....
ns, the two major groups of living mammals) that was particularly widespread 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 had never previously been found in the south (Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
). In 1990, Bonaparte named another species, Vucetichia gracilis, from Los Alamitos. He placed it in the family Gondwanatheriidae, together with 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....
, another Los Alamitos mammal, 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...
, which also contained the 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...
, then with the single genus 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"....
. Bonaparte considered the gondwanatheres to be probably most closely related to the 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 (sloths, armadillos, and anteaters) 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...
.
Also in 1990, Bonaparte merged the family Gondwanatheriidae into Sudamericidae and, together with David Krause, redefined Gondwanatheria as a multituberculate suborder that included both Ferugliotheriidae and Sudamericidae, thus rejecting a relationship between gondwanatheres and xenarthrans. 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...
redescribed Ferugliotherium in 1992 and suggested that the teeth that Vucetichia was based on may have been worn specimens of Ferugliotherium. They placed Ferugliotherium among multituberculates and suggested that it may be part of the suborder Plagiaulacoidea. The following year, Krause confirmed that Vucetichia gracilis is 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 windhauseni. Together with Bonaparte, he also proposed to classify gondwanatheres as a superfamily (Gondwanatherioidea) within Plagiaulacoidea, including the families Ferugliotheriidae and Sudamericidae. In 1996, Kielan-Jaworowska and Bonaparte tentatively identified a lower jaw fragment with a multituberculate-like fourth lower 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 as Ferugliotherium. On the basis of the morphological features of the jaw fragment, they argued that gondwanatheres 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 lower jaw of Sudamerica, which had previously only been known from isolated teeth. This jaw fragment showed that Sudamerica had four molariform (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"....
-like teeth) on each side of the lower jaws, more than any multituberculate, and consequently they removed gondwanatheres from Multituberculata and regarded their affinities as uncertain. As a consequence, Kielan-Jaworowska and colleagues excluded Gondwanatheria from multituberculates, but identified the jaw fragment and a few upper premolars of Ferugliotherium as indeterminate multituberculates in a 2001 paper and a 2004 book. However, in 2009 Yamila Gurovich and Robin Beck identified these fossils as Ferugliotherium and argued in favor of a close relationship between gondwanatheres (including Ferugliotheriidae) and multituberculates.
In the 2000s, additional members of Ferugliotheriidae were described. In 2004, Francisco Goin and colleagues described a single 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...
; their best estimate was that it represented a member of Ferugliotheriidae. On the basis of a single p4, Kielan-Jaworowska and colleagues named Argentodites coloniensis, from the Late Cretaceous 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....
of Argentina, in 2007 as a multituberculate, possibly referable to 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...
. However, Gurovich and Beck argued that the p4 of Argentodites did not differ materially from that in the jaw they allocated to Ferugliotherium, and that Argentodites was based on a specimen of either Ferugliotherium or a closely related animal. Guillermo Rougier and colleagues described mammals 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...
, a third Argentinean formation of similar age, in 2009, including a new ferugliotheriid, Trapalcotherium matuastensis. They also regarded Argentodites as a likely relative of Ferugliotherium and suggested that Ferugliotheriidae are either multituberculates or closely related to them.
Description
Ferugliotheriids are known from a few dozen isolated teeth and a questionably allocated jaw fragment. Most fossils are referred to Ferugliotherium; Trapalcotherium and Argentodites were each described on the basis of a single tooth. Their precise dental formula is unknown, but incisorIncisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
s, premolars, and molariform teeth have been identified. Gurovich suggested that Ferugliotherium 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.
Unlike the very high-crowned (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...
) sudamericids, ferugliotheriid teeth were low-crowned (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...
). Furthermore, sudamericid molariforms tend to be larger and are supported by one large root, but the smaller ferugliotheriids have at least two roots under their molariforms. Ferugliotherium is estimated to have weighed 70 g (2.5 oz).
The incisors, known only from Ferugliotherium, are procumbent and long. Three lower and four upper incisors are known. As is usual in mammals with similarly shaped (gliriform) incisors, the lower incisors are more laterally compressed, are less curved, form a greater angle between the front side and the wear facet at the tip, and are less elliptical in shape than the uppers. The enamel band is restricted to the side that faces the lips in both the lower and upper incisors (the lower side in the lowers and the upper side in the uppers).
The specimen MACN Pv-RN 975, first described by Kielan-Jaworowska and Bonaparte in 1996, may be a jaw fragment of Ferugliotherium, although it has also been identified as an unrelated multituberculate. The fossil preserves a bladelike premolar, identified as the fourth premolar, and the piece of the jawbone below it. 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) is present between the premolar and the incisor that would have been located in front of it. The alveolus
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...
(socket) of the lower incisor extends all the way through the fossil. The p4 bears eight ridges on both sides of the longitudinal crest and is supported by two roots at the front and back. The p4 assigned to Argentodites also has eight ridges on both sides, which descend from 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...
on the upper margin, and roots at the front and back. According to Kielan-Jaworowska and colleagues, it differs from that of MACN Pv-RN 975 in its rounded, as opposed to angular shape. However, Gurovich and Beck attribute this difference to the fact that the latter has undergone much more wear.
Two fossils have been interpreted as isolated lower premolars of Ferugliotherium; however, neither is still regarded as such. Two other teeth have been identified as upper premolars of Ferugliotherium; as with the jaw fragment, they may also represent an indeterminate multituberculate. One of the two preserves two longitudinal rows of cusps, of which one contains four and the other at least two cusps. The other is more poorly preserved, but may represent the same tooth position. These teeth resemble multituberculate upper premolars.
Four putative first lower molariforms (mf1s) of Ferugliotherium are known, and the only known tooth of Trapalcotherium is also thought to be an mf1. Ferugliotherium mf1s are roughly rectangular, with rounded corners, and bear two longitudinal rows of cusps. There are four cusps in the lingual row (on the side of the tongue) and three in the labial row (the side of the lips). The cusps are connected to cusps in the other row by transverse ridges and separated from cusps in their own rows by three transverse furrows. Two heavily worn Ferugliotherium mf1s were originally identified as upper molars of Vucetichia gracilis by Bonaparte in 1990. One of the two preserves the roots; at the front and back, there were two roots, fused at their bases. The mf1 of Trapalcotherium differs only in some details; among others, the cusps are less distinct from the crests. The sole mf2 of Ferugliotherium is the 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...
. It bears two rows of two cusps. The cusps in the front and back pairs are connected by a broad ridge and the two pairs are separated by a deep furrow. Transverse ridges between the cusps similar to those seen in ferugliotheriids are not known in any multituberculate. 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.
One Ferugliotherium tooth is thought to be a first upper molariform (MF1). It is almost rectangular and bears three longitudinal rows of cusps. There are five cusps in the middle row, which is oriented obliquely, four cusps in one of the rows on the side of the tooth, and two or three in the other row on the side. As in the lower molariforms, the cusps are connected by transverse ridges and separated by furrows. LACM 149371, the enigmatic possibly ferugliotheriid tooth from Peru, is a triangular tooth bearing six or seven cusps, which are connected by crests and surround two deep fossae (basins) and a third shallower fossa.
Range, ecology, and evolution
With its low-crowned teeth, Ferugliotherium may have been an insectivore or omnivore, like similar multituberculates such as MesodmaMesodma
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. The wear on Ferugliotherium teeth suggests that the animal may have eaten some plant material. The high-crowned sudamericids are thought to have been herbivores feeding on abrasive vegetation, although their precise diet is not known. In the evolutionary history of gondwanatheres, hypsodont teeth are thought to have evolved from brachydont precursors. Gurovich hypothesizes that the anterior molariforms of sudamericids may have evolved from bladelike premolars as seen in Ferugliotherium.
Fossils of Argentinean ferugliotheriids come from 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:...
(Ferugliotherium), La Colonia
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....
(Ferugliotherium and Argentodites), and 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...
s (Trapalcotherium). All three are approximately the same age, dating 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 mya) or more likely the 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 mya), but the La Colonia Formation is perhaps a little younger. The Los Alamitos and Allen Formations may have been deposited in a marshy environments, and the depositional environment of the La Colonia Formations may have been an estuary
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
, tidal flat, or coastal plain
Coastal plain
A coastal plain is an area of flat, low-lying land adjacent to a seacoast and separated from the interior by other features. One of the world's longest coastal plains is located in eastern South America. The southwestern coastal plain of North America is notable for its species diversity...
.
In each of the three formations, the mammalian fauna is dominated by the archaic 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...
; the Los Alamitos Formation has also produced the sudamericid Gondwanatherium and the possible triconodont Austroconodon. However, only seven mammalian teeth have been found in the Allen Formation. All three also contain remains of numerous other animals, including dinosaurs, amphibians, and fish.
The Santa Rosa fossil site, where LACM 149371 was found, is in the Ucayali Region
Ucayali Region
Ucayali is an inland region in Peru. Located in the Amazon rainforest, its name is derived from the Ucayali River. The regional capital is the city of Pucallpa.-Boundaries:...
of Peru. The Santa Rosa fauna also contains fossils of various unique species of marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
s and hystricognath rodents, a possible bat, and some notoungulates (a unique extinct group of South American ungulates). The age of this fauna is unclear, and estimates range from near the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
–Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
boundary (~35 mya) to the late Oligocene (~25 mya). The Santa Rosa mammals may have lived in a savanna
Savanna
A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...
habitat that contained rivers.
The range of the Ferugliotheriidae is narrower than that of Sudamericidae; sudamericids have been recorded from the Late Cretaceous (Gondwanatherium) and Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
(Sudamerica) of Argentina, the Late Cretaceous of Madagascar (Lavanify
Lavanify
Lavanify is a mammalian genus from the late Cretaceous of Madagascar. The only species, L. miolaka, is known from two isolated teeth, one of which is damaged. The teeth were collected in 1995–1996 and described in 1997...
) and India (Bharattherium
Bharattherium
Bharattherium is a mammal that lived in India during the Maastrichtian . The genus has a single species, Bharattherium bonapartei. It is part of the gondwanathere family Sudamericidae, which is also found in Madagascar and South America during the latest Cretaceous...
), the Middle Eocene of Antarctica (probably Sudamerica), and perhaps the Cretaceous of Tanzania (TNM 02067
TNM 02067
TNM 02067 is a fragmentary fossil dentary from the Cretaceous of Tanzania. The short, deep bone is about long, but the back part is broken off. It contains a large, forward-inclined incisor with a root that extends deep into the jaw, separated by a diastema from five cheekteeth...
, tentatively referred to Sudamericidae). Nevertheless, if LACM 149371 is a ferugliotheriid, it would likely represent the youngest record of gondwanatheres.