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Re: Asylosaurus and friends (now published).
I'll note that the paper is freely available here:
----- Original Message ----
From: Tim Williams <firstname.lastname@example.org>
To: email@example.com; firstname.lastname@example.org
Sent: Sunday, 16 March, 2008 7:56:50 PM
Subject: Asylosaurus and friends (now published).
This is a HUGE paper - so big that the journal (Revue de Paléobiologie) split
it into two files.
Galton, Peter M. (2007). Notes on the remains of archosaurian reptiles, mostly
basal sauropodomorph dinosaurs, from the 1834 fissure fill (Rhaetian, Upper
Triassic) at Clifton in Bristol, southwest England. Revue de Paléobiologie,
Genève 26 (2): 505-591.
Abstract: "Many of the best preserved teeth and bones of archosaurian reptiles
found in 1834 in an Upper Triassic Rhaetian fissure fill on Durdham
Down in Clifton (now in Bristol), southwest England were destroyed in 1940.
Based on an 1875 map, the site is positively identified
as within Quarry Steps Quarry. This paper includes an annotated catalogue,
copies of most of the illustrations from 1840 to 1908, and
photos of important extant specimens. Most of the recognizable, mostly
unassociated and incomplete bones have long been referred
to the basal sauropodomorph dinosaur _Thecodontosaurus_ Riley & Stutchbury,
1836 (as _T. antiquus_ Morris, 1843), with gracile
and robust morphs of several of the appendicular bones as a sexual dimorphism.
The deltopectoral crest of unassociated Clifton
humeri is plesiomorphic for basal sauropodomorphs, being anteroposteriorly high
and markedly asymmetrical in lateral view with a
short edge distal to the very prominent apex. The apex is at 40% (measured
perpendicular to long axis of humerus) of total length in
gracile ones and +50% in robust ones of the same size. However, the former
position is plesiomorphic for sauropodomorphs, the latter
derived, and no other basal sauropodomorph species h
rom Clifton, which
includes a forelimb and girdle, has a third humeral morph with a low
symmetrical deltopectoral crest with a rounded apex at 25% of
length. Whatever the status of the gracile and robust morphs, the characters
of referred postcranial bones from Clifton cannot be used
to distinguish the species of _Thecodontosaurus_ Riley & Stutchbury, 1836 that,
along with _T. antiquus_ Riley & Stutchbury vide
Owen, 1842, may be a nomen dubium. However, _T. antiquus_ is retained for the
slender humeral morph pending the description of
referred material from a Rhaetian fissure fill at Tytherington Quarry, Avon.
In the humerus of _Pantydraco_ (_Thecodontosaurus_) _caducus_
(Upper Triassic/Lower Jurassic, Wales) the apex of the asymmetrical
deltopectoral crest is at 40% of the length and the process is
low, a morph that is not represented at Clifton. The Clifton forelimb and
girdle is made the holotype of _Asylosaurus yalensis_ n. gen.
et sp. The manus shows lateral reduction, so phalangeal formula is 2-3-4-2-?1,
and the humerus has a large medial tubercle (small
in Welsh humerus). The other Clifton bones are identified as either: A. very
basal Sauropodomorpha indet (could be _Asylosaurus_ or
_Thecodontosaurus_, includes slender morph bones); B. Anchisauria indet (more
derived than A, includes robust morph bones); or C.
basal Sauropodomorpha indet (could be A or B).
"An ilium and two femora are very basal Theropoda (or possibly
Dinosauriformes); other theropod remains include a small tooth
crown with fine perpendicular denticles, a metacarpal I, a slender recurved
manual ungual, and an astragalus. A dorsal centrum may
be from an ornithischian dinosaur. _Rileyasuchus_ Kuhn, 1961 (type species
_Palaeosaurus platyodon_ Riley & Stutchbury, 1840), a
nomen dubium, is a heterodont crurotarsal phytosaur now represented by two
teeth and two humeri. The denticles are angled slightly
apically on the expanded mesial blade and perpendicular to the distal edge.
_Palaeosauriscus_ Kuhn, 1959 (type species _Palaeosaurus
Stutchbury, 1840) is based on lost teeth; it is Archosauria indet but may be a
valid taxon based on the
subcircular cross-section and fine, obliquely inclined denticles. A few bones
are none of the above and are Archosauria indet (dentary
with teeth, scapula-coracoid) and even Reptilia indet (?prootic, parietal,
distal femur, tibia, metapodial)."
_Thecodontosaurus antiquus_ looks like it might be safe as a valid taxon, based
on as-yet-published work. Says Galton: "_T. antiquus_ ... is provisionally
accepted as a valid taxon, the complete diagnosis of which awaits description
of the referred bones from Tytherington Quarry by Yates & Benton (in prep.)."
The new guy is _Asylosaurus yalensis_ (info taken directly from Galton
Etymology: Greek asylos = unharmed, safe from violence or asylon = refuge,
sanctuary + sauros = lizard; yalensis = of Yale College (now University), where
O. C. Marsh took specimen so it was unharmed in air raids on BCM in November,
Distribution: Upper Triassic (Rhaetian) of England.
Holotype: YPM 2195, an associated partial skeleton consisting of dorsal
vertebrae, ribs and gastralia, pectoral girdle, right and proximal left humeri,
articulated left forearm (radius very incomplete) and manus; also YPM 2195a-g,
disarticulated bones on block tentatively referred to holotype individual (or
species for femora), viz., vertebrae (cervical ~4 or 5, caudals ~10 and ~15),
proximal medial part of right ulna, distal left ischium, 2 distal femora:
larger right and smaller left, distal right tibia.
Hypodigm: proximal left humerus (BMNH R1542), manual phalanx 1 of digit I (YPM
56745), ischia (YPM 56725, 56726, 56739).
And, as the abstract says, _Palaeosauriscus_ might be a valid taxon - although
it's not clear what it actually is.
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