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NEW PERMO-TRIASSIC TRACK PAPERS
New issue of _Palaeontology_ arrived this morning.
Braddy, S. J., Morrisey, L. B. & Yates, A. M. 2003.
Amphibian swimming traces from the Lower Permian of
southern New Mexico. _Palaeontology_ 46, 671-683.
Some nice tracks from the Robledo Mountains ichnofauna
were produced by swimming tetrapods: though noted in
print before they'd been regarded as invertebrates traces
(which explains why Simon Braddy, best known for his
work on eurypterids, is involved). One set of tracks (a
sinusoidal, continuous body trace with paired manus and
pes prints) appears to have been produced by an 80-90 mm
long aquatic tetrapod with a salamander-like body shape.
The contendors considered are temnospondyls, microsaurs,
nectrideans or archeriids. Given the large adult sizes of
some of the members of these groups, the trackmaker may
have been a juvenile.
Rather more surprising is the new ichnotaxon
_Serpentichnus robledoensis_, a trace which recalls that
produced by side-winding snakes (i.e., in being
discontinuous and consisting of subparallel long body
traces) yet preserves pes impressions. Don't forget these
tracks were formed subaqueously. The trackmaker must
have been a long-bodied tetrapod (two trackways of this
taxon are reported, they represent animals with body lengths
of 160 and 240 mm respectively) with reduced limbs: the
only contendors are the lysorophians (aistopods are all
limbless and long-bodied microsaurs are not big enough or
long-bodied enough), with the Lower Permian
_Brachydectes_ being the most likely trackmaker. So, at
least some lysorophians were aquatic side-winders.. (!!),
how incredibly cool.
Rainforth, E. C. 2003. Revision and re-evaluation of the
Early Jurassic dinosaurian ichnogneus _Otozoum_.
_Palaeontology_ 46, 803-838.
A taxonomic revision and detailed discussion is given of
_Otozoum_. Suggested over the years to have been
produced by an ornithopod (Lull, Thulborn), plateosaur
(Nopsca) or basal thyreophoran (Gierlinski, Wright),
Rainforth shows that prosauropods (s. l.) best fit the
predicted trackmaker morphology: s. l. because
_Anchisaurus_ is suggested as the best trackmaker for N.
American _O. moodii_, while _Anchisaurus_,
_Ammosaurus_ and _Massospondylys_ are regarded as
good candidates for _O. pollex_ from Lesotho.
_Kalosauropus_ Ellenberger is sunk into _Otozoum_ and
Triassic tracks previously referred to _Otozoum_ are
actually the crurotarsan track _Pseudotetrasauropus_. There
is an interesting discussion of whether pad distribution
matches pedal osteology: while earlier authors (Hitchcock,
Lull, Heilmann etc) concluded that dinosaurs were either all
mesarthral (= pads underlying middle of phalanges) or all
arthral (= pads underlying interphalangeal joints), recent
work on birds (Rainforth cites Smith and Farlow, in press)
shows that, even within a species, there are arthal and
mesarthral individuals, and dinosaurs seem to have been
pretty variable. Presumably the arthral condition is primitive
for dinosaurs but various lineages may have evolved the
Other purported prosauropod trackways are reviewed and
characters observed in tracks are interpreted in a
phylogenetic framework. Surprisingly, prosauropod (s. l.)
tracks are absent from Late Triassic strata as Rainforth
shows that reports of such are erroneous.
There's more to it - anyone into tracks will get a lot out of
School of Earth & Environmental Sciences
University of Portsmouth UK, PO1 3QL
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