Pholidosaurus Purbeckensis

''Pholidosaurus'' is an extinct genus of neosuchian crocodylomorph. It is the type genus of the family Pholidosauridae. Fossils have been found in northwestern Germany. The genus is known to have existed during the Berriasian-Albian stages 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''.

Description

An early description of the genus by Lydekker (1888) mentioned that the orbit is slightly smaller than the supratemporal fossa, the nasals reach the premaxillae, and the vomer appears on the palate. It is similar in appearance to and about as large as the modern gharial.

Species

The type species of ''Pholidosaurus'' is ''P. schaumburgensis'', named in 1841 from the Wealden 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 Sandstein. This mould is known as IMGPGö 741-1. The individual that the mould belonged to is thought to have been around in length.

''Macrorhynchus'' is a junior synonym of ''Pholidosaurus''. It was named in 1843 from the same stratigraphic unit and region as ''P. schaumbergensis'', 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.

Misassigned species

''Pholidosaurus decipiens'' was erected for a partial cranium, NHMUK 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; NHMUK 28432 was reassigned to ''Pholidosaurus'' and NHMUK 41099 was designated the lectotype of ''Petrosuchus laevidens''. The species name ''decipiens'' was coined in reference to Owen's oversight, and ''Petrosuchus'' is now considered a junior synonym of '' Goniopholis simus''.

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'' an intermediate form between ''Steneosaurus'' and ''Teleosaurus''. However, in 2002, a new study showed that ''S. purbeckensis'' was conspecific with ''P. decipiens'', creating the new combination ''Pholidosaurus purbeckensis''.

Another species of ''Pholidosaurus'', ''P. laevis'', was named in 1913 from Swanage, based on the partial cranium NHMUK R3414. This has been considered a junior synonym of ''P. purbeckensis'' by both Salisbury ''et al.'' (1999) and Salisbury (2002).

In an SVPCA abstract, Smith ''et al.'' (2016) noted that ''Pholidosaurus purbeckensis'' is not congeneric with the type species, and instead is closely related to ''Fortignathus'' and members of Dyrosauridae.Thomas J. Smith, Lorna Steel, and Mark T. Young, 2016. Re-evaluation of ''Pholidosaurus purbeckensis'' (Crocodyliformes: Tethysuchia) from the Early Cretaceous of England, with implications for the evolution of Pholidosauridae and Dyrosauridae. ''Symposium of Vertebrate Palaeontology and Comparative Anatomy 2016 Abstract Book''. p. 29.

Classification

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 thalattosuchians. Buckley and Brochu (1999) concluded that ''Pholidosaurus'', ''Sokotosuchus'', Dyrosauridae, and Thalattosuchia formed a longirostrine clade that was the sister taxon to Crocodylia. However, Thalattosuchia was traditionally considered 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 as a more basal clade when dyrosaurids are removed from the data set.

More recent studies show that ''Pholidosaurus'' is closely related to the Thalattosuchia, with both taxa 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. Jouve ''et al.'' (2006) concluded that ''Pholidosaurus'' was closely related 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.

References

External links

''Pholidosaurus''
in the Paleobiology Database

{{Taxonbar, from=Q3381939

Early Cretaceous reptiles of Europe
Early Cretaceous crocodylomorphs of Europe
Neosuchians
Prehistoric pseudosuchian genera