Pachyrhachis (from Greek: παχύςpakhús, 'thick' and Greek: ῥάχῐςrhákhis, 'spine') is an extinct genus of snake with well developed hind legs known from fossils discovered in Ein Yabrud, near Ramallah, in the central West Bank. It is a relatively small snake, measuring more than 1.5 metres (4.9 ft) long at maximum.[1]Pachyrhachis appears to have been an ancient marine snake; the fossils occur in a marine limestone deposit, and the thickened bone of the ribs and vertebrae would have functioned as ballast to decrease the buoyancy of the animal, allowing it to dive beneath the ancient Cretaceous seas that it once inhabited.
Pachyrhachis is one of three genera of Cenomanian snakes with hindlimbs. Although many modern pythons and boas still retain remnants of legs, in the form of small spurs, the tiny legs of Pachyrhachis included a hip, knee, and ankle joint. Pachyrhachis was originally described by Haas (1979, 1980) who noted it had a puzzling melange of snake and lizard features; its status as an early snake was later confirmed (Caldwell and Lee 1997).
The position of Pachyrhachis within snakes has been debated (e.g. Lee and Scanlon 2002; Rieppel et al. 2003). Pachyrhachis is among the oldest known snakes and retains well-developed hind limbs, suggesting it represented a transitional form linking snakes to marine lizards (Lee and Scanlon 2002), though other studies place Pachyrhachis within the modern snake radiation as stem-Macrostomata (Zaher, 1998; Zaher & Rieppel, 1999).
^Bardet, Nathalie (2008). "The Cenomanian-Turonian (late Cretaceous) radiation of marine squamates (Reptilia): the role of the Mediterranean Tethys". Bulletin de la Société Géologique de France. 179 (6): 605–623. doi:10.2113/gssgfbull.179.6.605.
the form of small spurs, the tiny legs of Pachyrhachis included a hip, knee, and ankle joint. Pachyrhachis was originally described by Haas (1979, 1980)...
lizards. Ophidia was defined as the "most recent common ancestor of Pachyrhachis and Serpentes (modern snakes), and all its descendants" by Lee and Caldwell...
to be more plesiomorphic than other Cretaceous limbed snakes, such as Pachyrhachis, Haasiophis or Eupodophis, in retaining a sacro-iliac contact and well-developed...
Along with its sister genus Pachyrhachis, Haasiophis does not possess either a sacral rib or vertebrae. Also like Pachyrhachis there is no preserved indication...
connection to the vertebrae. These include fossil species like Haasiophis, Pachyrhachis and Eupodophis, which are slightly older than Najash. This hypothesis...
name Bulbophyllum pinelianum (A.Rich.) Paul Abel Ormerod 2016 Synonyms Pachyrhachis pineliana A.Rich. Pleurothallis pachyrachis A.Rich. in R.de la Sagra...
PMID 30718525. Other known fossil snakes with developed hindlimbs, Haasiophis, Pachyrhachis and Eupodophis—all found in marine environments—all lack a sacral region...
characterized by the presence of hindlimbs and pelvic girdles, as seen in Pachyrhachis (one of the first discovered hind-limbed snakes). Included in the most...
were three other known species of legged snakes from this time period, Pachyrhachis problematicus, Haasiophis terrasanctus and Eupodophis descouensi, but...
portal List of transitional fossils Other known fossil snakes with legs: Pachyrhachis Haasiophis Najash "Fossilized Snake With Two Legs Found - Science - redOrbit"...
Caldwell, Michael W. (29 October 1998). "Anatomy and relationships of Pachyrhachis problematicus, a primitive snake with hindlimbs". Philosophical Transactions...
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