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mega orcas revisited
Greatings to all
I'm back after a winter of good field trips and complete chaos as they
refurbish ( = destroy and then rebuild) our building. Collected a bit
of Kronosaurus whilst out West - a bit a belly with some elasmosaur
vertebrae and gastroliths inside it - and we also came across a nice
elasmosaur (nearly all there apart from the head, unfortunately).
Anyway, I meant to add something to the posting Dazzer put up a few
months ago on Mega-Orcas (13th June, I think), so here it is.
This (Northern) summer the BMNH put back on display their Mesozoic marine
reptiles, after the specimens spent 7 years at the Doctors' (so to
speak). Of special interest (to me at least) are the various Jurassic
pliosaurs included within this display, and I look forward to seeing them
more closely next year. Rhomaleosaurus (which includes the
'gracile' R.megacephalus and the more 'robust' R.zetlandicus, the latter
was described my Mike Taylor (now at Edinburugh)) is from the Lower
Jurassic. The Upper Jurassic forms include the smaller (relatively -
about 5 metres long?) Peloneustes and Simolestes (whose mandibles are
very differently shaped, perhaps idicating specialised piscivore and
respectively?), the medium sized Pliosaurus (includes 3 species -
P.brachydeirus, P.brachyspondylus, and P.andrewsi), and the giant
Liopleurodon (L.ferox, L.pachydeirus, and L. macromerus). Exactly how
all these ulta-predators were making a living (in the same communities?)
is a question worthy of an enterprising Ph.D...
The last major review of these beasts was done by the late great Bev
Halstead/Tarlo, in 1960 (L.B. Tarlo, Bull. Brit. Mus. (nat Hist.), Geol.,
4 (5) 147-189), and little has been done since. In that review he
describes L.macromerus as belonging to the genus Stretosaurus, a genus he
erected in 1959, noting "The pectoral girdle of this animal is so unusual
that a new generic name is considered necessary for its reception"
(Tarlo, L.B. Palaeontology, 2, 39-55). For a while Stretosaurus got into
the books as a huge cousin of Liopleurodon, bigger perhaps than
Kronosaurus (there are tales of a 3 metre mandible, which would certainly
qualify it for contention), but in 1975 a new Liopleurodon was found
which made him realise that what he had thought was the pectoral girdle in
Stretosaurus was in fact the pelvic girdle, and he thus put S. macromerus
into Liopleurodon (an easy mistake to make, given the scrappiness of the
larger pliosaur specimens) (Halstead, L.B., 1989, J. Geol. Soc., Lond.,
After 1975 there was a rush on re-interpretations of plesiosaurian
swimming and feeding, and in 1992 Mike Taylor published his description
of the head of Rhomealosaurus zetlandicus (Phil. Trans. R. Soc. Lond.,
ser. B, 335, 247-280). Mike and Arthur Cruickshank have since done some
more work on pliosaurs, including a description of well developed
underwater olfaction...! Last year (just befor I left the U.K. to come
here for the kronosaurs) there was a large (complete?) pliosaur found in
clay near Westbury, and I think Glenn Stores (now at Cincinati) has got
his hands on it. A species of Pliosaurus, I think.
There were supposed to be some biggy's in N. America as well, during the
Cretaceous this time. When he was setting the stage for Kronosaurus in
1930, Heber Longman mentions Megalneusaurus rex (as an inferior, of
course), but I've heard very little of it. Do our American cousins know
anything of this beast?
Down here in the South Kronosaurus rules the roost, with a number of
specimens from Queensland (one of which can be seen at Harvard - but it
doesn't really look like that), and some from Columbia. Oliver Hampe has
described the S. American ones as K. boyacensis (Courier Forsch.-Inst.
Senckenberg, 145: 1-32 - I'll read it as soon as I get it translated!),
and I would like to get a look at them. The ones over here are K.
queenslandicus. Other Australian pliosaurs include Eric the opalised
pliosaur (yet more antipodean pythonisms), a specimen found in fresh
water deposits whose name escapes me, and another (smaller) beast from
the same rocks as Kronosaurus, but which has a huge neck, larger
forelimbs than hind, and a fish eating skull that looks just like that of
the fresh water croc which we get here (yet to be named - the pliosaur,
that is, not the croc).
Darren, I'd say that all the plesiosaurs ingested (hard volcanic) stones
for ballast - they are present in at least one Kronosaurus specimen, and
quite a few of the Woolungasurus specimens (the local elasmosaur) in the
Enough for now.
Vert. Palaeo. Lab.