Pholidosaurus
Encyclopedia
Pholidosaurus is an extinct genus
of neosuchia
n crocodylomorph. It is the type genus
of the family
Pholidosauridae
. Fossils have been found from Germany
and England
. The genus is known to have existed during the Berriasian
stage of the Early Cretaceous
. Fossil material found from the Annero and Jydegård Formations in Skåne, Sweden
and on the island of Bornholm
, Denmark
, have been referred to as a mesoeucrocodylian, and possibly represent the genus Pholidosaurus.
is slightly smaller than the supratemporal fossa, the nasals
reach the premaxilla
e, and the vomer
appears on the palate
. It is similar in appearance to and about as large as the modern gharial
.
of Pholidosaurus is P. schaumburgensis, named in 1841 from the Wealden
, or Hastings Sand, of Bückeburg
, Germany. P. schaumburgensis was named on the basis of a natural mould of part of a thorax discovered in around 1830 from the Berriasian Obernkirchen Sandstone. This mould is known as IMGPGö 741-1. The individual that the mould belonged to is thought to have been around 25 centimetres (9.8 in) in length.
Macrorhynchus is a junior synonym
of Pholidosaurus. It was named in 1843 from the Wealden Group in southern England, with the type species being M. meyeri. Because M. meyeri bears a strong resemblance to Pholidosaurus schaumburgensis, it is now regarded as a species of Pholidosaurus. It was reassigned to the genus Pholidosaurus in 1887 by Richard Lydekker
because of this synonymy, and also because the name Macrorhynchus was preoccupied by a genus of fish named in 1880. P. meyeri differs from P. schaumburgensis in that the bar separating the supratemporal fenestrae is rounded, while in the type species it is rounded.
Several species of Pholidosaurus have been named in the past, but are no longer considered valid. These include P. decipiens and P. laevis. P. decipiens was constructed to describe a partial cranium, BMNH 28432, that was originally assigned to the new genus and species Petrosuchus laevidens by Richard Owen
in 1878. Petrosuchus laevidens was based on this cranium and a mandibular ramus called BMNH 41099, both of which were collected from Swanage
, England. A later study in 1911 concluded that the material belonged to two different species. BMNH 28432 was reassigned to Pholidosaurus and BMNH 41099 was referred to the retained name Petrosuchus laevidens. BMNH 28432 was designated as the lectotype
of the new species Pholidosaurus decipiens, named in reference to Owen's oversight.
Another species from England, P. purbeckensis, was originally described as a species of Steneosaurus
in 1888. The holotype is an almost complete cranium, referred to as DORCM G97, missing the anterior portion of the rostrum. The skull was found from either Swanage or the Isle of Purbeck
(hence the species name), although the exact locality from which the skull originated is not specified by the author of the original description. This material was also once referred to Macrorhynchus. The author of the 1888 description considered S. purbeckensis to be an intermediate form between Steneosaurus and Teleosaurus
. However, in 2002, a new study proposed that S. purbeckensis belonged to P. decipiens. Because the name S. purbeckensis had seniority over P. decipiens, but not the genus Pholidosaurus, the name Pholidosaurus purbeckensis is considered to have priority.
Another species of Pholidosaurus, P. laevis, was named in 1913 from Swanage, based on a partial cranium known as BMNH R3414. This has been considered a junior synonym of P. purbeckensis by both Salisbury et al. (1999) and Salisbury (2002).
Sereno et al. 2001
Pol 2003
Richard Lydekker assigned Pholidosaurus to the family Goniopholididae
in 1887 along with Hylaeochampsa
, Theriosuchus
, Goniopholis
, and Petrosuchus because the vertebrae are amphicoelus and the orbit communicates with the lateral temporal fossa
.
Pholidosaurus has often been grouped with other longirostrine, or long-snouted, crocodylomorphs, including dyrosaurids
and thalattosuchia
ns. Buckley and Brochu (1999) concluded that Pholidosaurus, Sokotosuchus
, Dyrosauridae, and Thalattosuchia formed a longirostrine clade
which was the sister taxon to Crocodylia. However, Thalattosuchia was traditionally regarded to be a more basal clade of crocodylomorphs, being a more basal lineage of Mesoeucrocodylia
than dyrosaurids or Pholidosaurus, both of which were considered neosuchians. The results of the phylogenetic analysis by Buckley and Brochu (1999) were attributed to the similarity in characters associated with snout elongation seen in these crocodylomorphs, even though these characters may have been independently derived
in each group. More recent studies have revealed Thalattosuchia to be a more basal clade when dyrosaurids are removed from the data set.
More recent studies have shown Pholidosaurus to be the closely related to the Thalattosuchia, with both taxa being closely related to a clade containing Terminonaris
and the Dyrosauridae. In a phylogenetic analysis conducted by Sereno et al. (2001), Pholidosaurus was placed as a distant sister taxon to the other longirostrine crocodylomorphs, with Terminonaris and the newly named Sarcosuchus
being closely related to one another and Dyrosaurus
being the next closest taxon to the group. The later phylogenetic analysis of Brochu et al. (2002) again showed that Pholidosaurus was closely related to Thalattosuchia. In the study, both taxa formed a clade that was the sister taxon to a clade containing Sokotosuchus and Dyrosauridae.
Pholidosaurus has recently been reassigned to the family Pholidosauridae, along with the genera Elosuchus
, Sarcosuchus, and Termionaris. Jouve et al. (2006) concluded that Pholidosaurus was a pholidosaurid, although in their phylogenetic analysis, thalattosuchians were also included within the family, which would be considered paraphyletic without them. Jouve et al. (2006), like Buckley and Brochu (1999), attributed this result to phylogenetic problems that exist among longirostrine crocodylomorphs due to similarities in their morphology.
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...
of neosuchia
Neosuchia
Neosuchia is an unranked clade within Mesoeucrocodylia that includes all modern extant crocodilians and their closest fossil relatives. It is defined as the most inclusive clade containing all crocodylomorphs more closely related to Crocodylus niloticus than to Notosuchus terrestris...
n crocodylomorph. It is the type genus
Type genus
In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...
of the 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...
Pholidosauridae
Pholidosauridae
Pholidosauridae is an extinct family of mesoeucrocodylian crocodylomorphs. Fossils have been found in the United States, Canada, China, Kyrgyzstan, Africa and Spain...
. Fossils have been found from Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
and England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. The genus is known to have existed during the Berriasian
Berriasian
In the geological timescale, the Berriasian is an age or stage of the Early or Lower Creteceous. It is the oldest or lowest subdivision in the entire Cretaceous. It spanned between 145.5 ± 4.0 Ma and 140.2 ± 3.0 Ma...
stage of the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
. Fossil material found from the Annero and Jydegård Formations in Skåne, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
and on the island of Bornholm
Bornholm
Bornholm is a Danish island in the Baltic Sea located to the east of the rest of Denmark, the south of Sweden, and the north of Poland. The main industries on the island include fishing, arts and crafts like glass making and pottery using locally worked clay, and dairy farming. Tourism is...
, Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
, have been referred to as a mesoeucrocodylian, and possibly represent the genus Pholidosaurus.
Description
An early description of the genus by Lydekker (1888) mentioned that the orbitOrbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
is slightly smaller than the supratemporal fossa, the nasals
Nasal bone
The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face, and form, by their junction, "the bridge" of the nose.Each has two surfaces and four borders....
reach the premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
e, and the vomer
Vomer
The vomer is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones.-Biology:...
appears on the palate
Palate
The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...
. It is similar in appearance to and about as large as the modern gharial
Gharial
The gharial , , also called Indian gavial or gavial, is the only surviving member of the once well-represented family Gavialidae, a long-established group of crocodilians with long, slender snouts...
.
Species
The type speciesType species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of Pholidosaurus is P. schaumburgensis, named in 1841 from the Wealden
Wealden Group
The Wealden Group is a group in the lithostratigraphy of southern England. The Wealden group consists of paralic to continental facies sedimentary rocks of Valanginian to Barremian age and thus forms part of the English Lower Cretaceous. It is composed of alternating sands and clays...
, or Hastings Sand, of Bückeburg
Bückeburg
Bückeburg is a town in Lower Saxony, Germany, on the border with North Rhine Westphalia. It was once the capital of the tiny principality of Schaumburg-Lippe and is today located in the district of Schaumburg close to the northern slopes of the Weserbergland ridge...
, Germany. P. schaumburgensis was named on the basis of a natural mould of part of a thorax discovered in around 1830 from the Berriasian Obernkirchen Sandstone. This mould is known as IMGPGö 741-1. The individual that the mould belonged to is thought to have been around 25 centimetres (9.8 in) in length.
Macrorhynchus is a junior 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 Pholidosaurus. It was named in 1843 from the Wealden Group in southern England, with the type species being M. meyeri. Because M. meyeri bears a strong resemblance to Pholidosaurus schaumburgensis, it is now regarded as a species of Pholidosaurus. It was reassigned to the genus Pholidosaurus in 1887 by Richard Lydekker
Richard Lydekker
Richard Lydekker was an English naturalist, geologist and writer of numerous books on natural history.-Biography:...
because of this synonymy, and also because the name Macrorhynchus was preoccupied by a genus of fish named in 1880. P. meyeri differs from P. schaumburgensis in that the bar separating the supratemporal fenestrae is rounded, while in the type species it is rounded.
Several species of Pholidosaurus have been named in the past, but are no longer considered valid. These include P. decipiens and P. laevis. P. decipiens was constructed to describe a partial cranium, BMNH 28432, that was originally assigned to the new genus and species Petrosuchus laevidens by Richard Owen
Richard Owen
Sir Richard Owen, FRS KCB was an English biologist, comparative anatomist and palaeontologist.Owen is probably best remembered today for coining the word Dinosauria and for his outspoken opposition to Charles Darwin's theory of evolution by natural selection...
in 1878. Petrosuchus laevidens was based on this cranium and a mandibular ramus called BMNH 41099, both of which were collected from Swanage
Swanage
Swanage is a coastal town and civil parish in the south east of Dorset, England. It is situated at the eastern end of the Isle of Purbeck, approximately 10 km south of Poole and 40 km east of Dorchester. The parish has a population of 10,124 . Nearby are Ballard Down and Old Harry Rocks,...
, England. A later study in 1911 concluded that the material belonged to two different species. BMNH 28432 was reassigned to Pholidosaurus and BMNH 41099 was referred to the retained name Petrosuchus laevidens. BMNH 28432 was designated as the lectotype
Lectotype
In botanical nomenclature and zoological nomenclature, a lectotype is a kind of name-bearing type. When a species was originally described on the basis of a name-bearing type consisting of multiple specimens, one of those may be designated as the lectotype...
of the new species Pholidosaurus decipiens, named in reference to Owen's oversight.
Another species from England, P. purbeckensis, was originally described as a species of Steneosaurus
Steneosaurus
Steneosaurus is an extinct genus of teleosaurid crocodyliform from the Early Jurassic to Early Cretaceous . Fossil specimens have been found in England, France, Germany, Switzerland and Morocco.-Species:...
in 1888. The holotype is an almost complete cranium, referred to as DORCM G97, missing the anterior portion of the rostrum. The skull was found from either Swanage or the Isle of Purbeck
Isle of Purbeck
The Isle of Purbeck, not a true island but a peninsula, is in the county of Dorset, England. It is bordered by the English Channel to the south and east, where steep cliffs fall to the sea; and by the marshy lands of the River Frome and Poole Harbour to the north. Its western boundary is less well...
(hence the species name), although the exact locality from which the skull originated is not specified by the author of the original description. This material was also once referred to Macrorhynchus. The author of the 1888 description considered S. purbeckensis to be an intermediate form between Steneosaurus and Teleosaurus
Teleosaurus
Teleosaurus was an extinct genus of teleosaurid crocodyliform that lived during the Middle Jurassic. It was approximately in length. Teleosaurus had highly elongate jaws, similar to those of a modern gharial. It had a long, slender, body, with a sinuous tail that would have helped propel it...
. However, in 2002, a new study proposed that S. purbeckensis belonged to P. decipiens. Because the name S. purbeckensis had seniority over P. decipiens, but not the genus Pholidosaurus, the name Pholidosaurus purbeckensis is considered to have priority.
Another species of Pholidosaurus, P. laevis, was named in 1913 from Swanage, based on a partial cranium known as BMNH R3414. This has been considered a junior synonym of P. purbeckensis by both Salisbury et al. (1999) and Salisbury (2002).
Classification
Richard Lydekker assigned Pholidosaurus to the family Goniopholididae
Goniopholididae
Goniopholididae is an extinct family of moderate-sized semi-aquatic crocodyliforms similar to living crocodiles. They lived between the Early Jurassic and the Late Cretaceous.-Geographical distribution:...
in 1887 along with Hylaeochampsa
Hylaeochampsa
Hylaeochampsa is an extinct genus of eusuchian crocodylomorph. It is known only from a partial skull recovered from Barremian-age rocks of the Lower Cretaceous Vectis Formation of the Isle of Wight. This skull, BMNH R 177, is short and wide, with a eusuchian-like palate and inferred enlarged...
, Theriosuchus
Theriosuchus
Theriosuchus is an extinct genus of atoposaurid mesoeucrocodylian from the Late Jurassic of Europe, the Early Cretaceous of Asia and the Late Cretaceous of Romania. The five species are T. pusillus from England , T. ibericus from Spain , T. guimarotae from Portugal , T. sympiestodon from Romania...
, Goniopholis
Goniopholis
Goniopholis is an extinct genus of crocodyliform that lived in North America, Europe and Asia during the Late Jurassic and Early Cretaceous. Being semi-aquatic it is very similar to modern crocodiles...
, and Petrosuchus because the vertebrae are amphicoelus and the orbit communicates with the lateral temporal fossa
Temporal fossa
The temporal fossa is a shallow depression on the side of the skull bounded by the temporal lines and terminating below the level of the zygomatic arch.-Boundaries:...
.
Pholidosaurus has often been grouped with other longirostrine, or long-snouted, crocodylomorphs, including dyrosaurids
Dyrosauridae
Dyrosauridae is a family of extinct neosuchian crocodyliforms that lived from the Late Cretaceous to the Eocene. Fossils of this group have been found in almost every continent, specifically Africa, Asia, Europe, North America and South America....
and thalattosuchia
Thalattosuchia
Thalattosuchia is the name given to a clade of marine crocodylomorphs from the Early Jurassic to the Early Cretaceous that had a cosmopolitan distribution. They are sometimes colloquially referred to as marine crocodiles or sea crocodiles, though they are not actually members of Crocodilia.The term...
ns. Buckley and Brochu (1999) concluded that Pholidosaurus, Sokotosuchus
Sokotosuchus
Sokotosuchus is an extinct genus of dyrosaurid crocodyliform which existed in Africa.-External links:* at the Paleobiology Database...
, Dyrosauridae, and Thalattosuchia formed a longirostrine clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
which was the sister taxon to Crocodylia. However, Thalattosuchia was traditionally regarded to be a more basal clade of crocodylomorphs, being a more basal lineage of Mesoeucrocodylia
Mesoeucrocodylia
Mesoeucrocodylia is the name of the clade that includes Eusuchia and the paraphyletic group Mesosuchia. The group appeared during the Early Jurassic, and continues to the present day....
than dyrosaurids or Pholidosaurus, both of which were considered neosuchians. The results of the phylogenetic analysis by Buckley and Brochu (1999) were attributed to the similarity in characters associated with snout elongation seen in these crocodylomorphs, even though these characters may have been independently derived
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
in each group. More recent studies have revealed Thalattosuchia to be a more basal clade when dyrosaurids are removed from the data set.
More recent studies have shown Pholidosaurus to be the closely related to the Thalattosuchia, with both taxa being closely related to a clade containing Terminonaris
Terminonaris
Terminonaris is a genus of extinct crocodilian reptiles that lived in the Late Cretaceous . Its remains are known from North America...
and the Dyrosauridae. In a phylogenetic analysis conducted by Sereno et al. (2001), Pholidosaurus was placed as a distant sister taxon to the other longirostrine crocodylomorphs, with Terminonaris and the newly named Sarcosuchus
Sarcosuchus
Sarcosuchus is an extinct genus of crocodyliform and distant relative of the crocodile that lived 112 million years ago. It dates from the early Cretaceous Period of what is now Africa and is one of the largest giant crocodile-like reptiles that ever lived...
being closely related to one another and Dyrosaurus
Dyrosaurus
Dyrosaurus was an extinct genus of dyrosaurid crocodyliform from the Eocene of North Africa. The type species D. phosphaticus possessed slender jaws with numerous recurved teeth, indicative of a primarily fish diet...
being the next closest taxon to the group. The later phylogenetic analysis of Brochu et al. (2002) again showed that Pholidosaurus was closely related to Thalattosuchia. In the study, both taxa formed a clade that was the sister taxon to a clade containing Sokotosuchus and Dyrosauridae.
Pholidosaurus has recently been reassigned to the family Pholidosauridae, along with the genera Elosuchus
Elosuchus
Elosuchus is an extinct genus of neosuchian crocodyliform that lived during the Early Cretaceous of what is now North Africa ....
, Sarcosuchus, and Termionaris. Jouve et al. (2006) concluded that Pholidosaurus was a pholidosaurid, although in their phylogenetic analysis, thalattosuchians were also included within the family, which would be considered paraphyletic without them. Jouve et al. (2006), like Buckley and Brochu (1999), attributed this result to phylogenetic problems that exist among longirostrine crocodylomorphs due to similarities in their morphology.
External links
- Pholidosaurus in the Paleobiology DatabasePaleobiology Database' is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms.-History:The Paleobiology Database was founded in 2000. It has been funded by the National Science Foundation and the Australian Research Council...