User:Horus-Horakhty/sandbox

Horus-Horakhty/sandbox Temporal range: Ypresian - Priabonian, Possible Cenomanian - Maastrichtian record
Fossil vertebrae of Palaeophis maghrebianus from Khouribga (Morocco)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Family:	†Palaeophiidae
Subfamily:	†Palaeophiinae
Genus:	†Palaeophis Owen, 1841
Type species
†Palaeophis toliapicus Owen, 1841
Species
Species †Palaeophis africanus Andrews 1924 †Palaeophis casei Holman 1982 †Palaeophis colossaeus Rage 1983 †Palaeophis ferganicus Averianov 1997 †Palaeophis grandis Marsh 1869 †Palaeophis littoralis Cope 1847 †Palaeophis maghrebianus Arambourg 1952 †Palaeophis nessovi Averianov 1997 †Palaeophis oweni Zigno 1881 †Palaeophis tamdy Averianov 1997 †Palaeophis toliapicus Owen 1841(type) †Palaeophis typhaeus Owen 1850 †Palaeophis vastaniensis Bajpai & Head 2008 †Palaeophis virginianus Lynn 1934 †Palaeophis zhylan Averianov 1997
Synonyms
Dinophis (Marsh, 1869) Titanophis (Marsh, 1878) Vialovophis (Averianov, 1997)

Palaeophis is an extinct genus of aquatic snake belonging to the extinct snake family Palaeophiidae.

Described species within this genus lived mainly during the Eocene epoch, with some unnamed or questionable records from the Cenomanian, Maastrichtian and the Palaeocene.

Description

From the ancient greek παλαιός, palaiós (« ancient ») et ὄφις, óphis (« snake »), Palaeophis was originally described by Richard Owen in 1841, using fossils of the species P. toliapicus from the London Clay. It is one of the first genus of fossil snake known.

Anatomy

As in most fossil snakes species, the anatomy of the genus is known solely through vertebrae and ribs, isolated or articulated. Their morphology reveals a strong modification, due to the high aquatic specialisation of these animals. No skull elements have been described yet.

Vertebrae

The vertebrae are characterised by a marked lateral compression, a tall and thin neural spine (rarely preserved on fossils), a horizontal condyle axis, synapophyses (ribs connexion area) low on the centrum, a hypapophysis (bony projection below the vertebra) occurs on all trunk vertebrae, preceding a second anterior hypapophysis on the anterior trunk region only. The pterapophysis, bony posterior projections of the neural arch and characteristic of the Palaeophiidae, can be more or strongly defined, depending on the species. Differing from the genus Pterosphenus, the neural spine does not extends to the front of the zygosphene in Palaeophis.

The vertebrae can have an overall robust morphology, as seen in P. colossaeus or P. maghrebianus, or more slender and lightly built, as in P. toliapicus and P. typhaeus, without however reaching the more extreme morphology of Pterosphenus. The many species of Palaeophis can thus be separated into two assemblages of species or grades. In which the primitive grade include species whose vertebrae are weakly laterally compressed and have less developed and low process of vertebrae. Subsequently the advanced grade are characterized by vertebrae presenting a strong lateral compression which translate to being much better adaption to aquatic life.

Ribs

The ribs are slender, long and barely curved, giving a laterally flattened shape to the whole body of the snake, reminiscing of the overall appearance of extant Hydrophiinae sea snakes. This "eel-like" morphology enable efficient active propulsion of the animal in the aquatic environment, using its body as a fin.

Microanatomy and metabolism

Illustration of articulated vertebrae of P. toliapicus

The internal anatomy of vertebrae from P. maghrebianus show a high degree of internal vascularisation, superior to the one of the green anaconda or the reticulated python, suggesting a quick growth and a fastest metabolism than any of today's biggest snakes. Traces of osteosclerosis have also been observed in P. maghrabianus, and while not found in the species P. colossaeus, P. toliapicus and P. typhaeus, could be an eventual proof of its adaptation to a shallow water environment.

Size estimations

Palaeophis colossaeus size estimations compared to other large snakes.

Snakes of the genus Palaeophis varied broadly in size, starting with Palaeophis casei being the smallest at 1.6 m (5.2 ft) of length, but most of them were overall imposing animals. The largest species, Palaeophis colossaeus, is estimated to have been 8.1–12.3 m (27–40 ft) long based on isolated vertebrae, making it the second biggest snake known, after Titanoboa cerrejonensis. P. maghrebianus was estimated at a slightly inferior or similar size. Based on more or less complete vertebrae, simulation models applied to P. africanus reveal a length of 4.3–6.5 m (14–21 ft) for the biggest specimens.

Ecology and behaviour

Restoration of Palaeophis maghrebianus

Based on the highly fragmentary nature of Palaeophis fossils, few interpretations about the ethology of the genus can be made apart from its strong aquatic specialisation. Often found associated with fossils of fish, sirenians, turtles, crocodiles, lizards, terrestrial mammals and other snakes, Palaeophis could have been an opportunistic active predator or an exclusive piscivore.

Habitat and repartition

There is an overall global repartition of the genus Palaeophis through the beginning of the Paleogene, with fossils found in Angola (P. africanus), Belgium (P. toliapicus, P. typhaeus), Denmark (P. toliapicus), England (P. toliapicus, P. typhaeus), France (P. toliapicus, P. typhaeus), India (P. vastaniensis), Italy (P. oweni), Kazakhstan (P. nessovi, P. zhylan), Kyrgyzstan (P. ferganicus), Mali (P. colossaeus), Morocco (P. maghrebianus), Nigeria (P. africanus), Togo (P. africanus), Ukraine (P. nessovi), United States (P. africanus, P. casei, P. grandis, P. littoralis, P. virginianus) and Uzbekistan (P. tamdy).

As for most Palaeophiidae, Palaeophis fossils occur primarily in shallow marine strata, though at least some estuarine remains have also been found.

References

Category:Eocene snakes Category:Paleocene reptiles of Europe Category:Paleogene reptiles of Africa Category:Eocene reptiles of Europe Category:Taxa named by Richard Owen Category:Fossil taxa described in 1841 Category:Fossils of Denmark Category:Fur Formation

Category:Fossils of Mali