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PTEROSAUR TRACKS



Betty C mentioned some stuff on pterosaur prints and quoted a bit from
Wellnhofer's book where he says..

> "So far there have been no confirmed
> finds of pterasaur footprints, so conclusive proof of this is
> unavailable".  

In the last couple of years, alleged pterosaur tracks have been turning up all
over the place and there are quite a few publications on them. The N. American
_Pteraichnus_ tracks, which Padian has argued (and still does I think) were made
by crocodiles and don't match pterosaur morphology, are generally thought to be
pterosaurian after all and prints damn near identical are now known from other
N. American sites as well as from Europe at least. Here in Europe we have lots
of such prints form Spain and really big ones have now been reported from the
Purbeck Fm (_Palaeontology Newsletter_ 32, 1996). I recall a mention somewhere
of a trackway where the manus would have been 30 cm or so long: this is a *big*
animal.

Some superb examples from the Tithonian of Quercy, France, were published (1995)
in _Comptes Rendu_ and preserve foot impressions so well I find it difficult to
_doubt_ that they are pterosaurian. They are plantigrade, webbed, and a
distinctive pterosaurian character is (let's hope I get this bit right) a
shortened penultimate phalanx on digit 1. This feature occurs recurrently in
these new pterosaur tracks (incl. all _Pteraichnus_ ones). It matches pterosaur
osteology and isn't seen in any other tetrapod.

Manus prints in all of these trackways show that the pterosaurs were walking
quadrupedally (no surprise) and the forelimbs are rather wide gauge - that is,
they are put down outside of the parallel lines made by the hindfeet. Manus
prints, if memory serves, typically depict three fingers and there is
occasionally a imprint which suggests the base of the wing finger. A recent
objection from Gareth Dyke (who has just finished _his_ dissertation on
pterosaur phylogeny, let's hope he can get it published) is that the pterosaur
would have had to do some funny wrist twisting to get the manus long axis
perpendicular to the body length. I don't see this as a problem if the elbows
were bowed out, but admittedly I'm hazy right now on how the humerus and glenoid
articulated in these animals (hey, ask me about plesiosaur humeral movement: no
problem.. pterosaurs.. err, where's Dave Peters?).

All these discoveries tell us something about pterosaur ecology, and something
that isn't terribly surprising. They were spending a lot of time walking around
on mudflats. Well, even without the tracks, I'd like to think you could have
guessed that. Nearly all known pterosaurs are sea/shorebird analogues - go down
to a muddy beach and you'll see sea/shorebird prints all over the place.

I should note, should someone with a lot more clout come along, that a lot of
this is disputed by some pterosaur workers. Kevin Padian in particular would not
agree with any of these interpretations (the plantigrade foot, quadrupedal
stance, wide-gauge forelimbs). Dave Peters has suggested (at last SVP meeting
and in _JVP_ 16) that a plantigrade foot was evolved in filter-feeding
pterodaustrids and ctenochasmatids as an adaptation for wading. I think this is
fair enough, but, then.. I'm not a pterosaur expert. Controversial animals.

"Moff Tarkin: I should have recognised your foul stench when I set foot onboard"

"Stay in attack formation"

DARREN NAISH