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Re: On Mesozoic "birds" and Eocene whales



Aspidel wrote:
>
> No, but already _Mosasaurus hoffmanni_. -;)
>
And don't forget about the recently described species: Prognathodon
saturator.

Prognathodon saturator

Species name meaning: he-who-gives-satisfaction; species name given because
it's is always good to find a new species of Mosasaur, as felt by the
discoverer of this specimen, Rudi Dortangs, or another meaning: the dead
remains gave "satisfaction" to the sharks that had been eating the carcass
when it was lying on the ocean floor;

Literature in which Prognathodon saturator is described/ mentioned:

- Prognathodon saturator - a large new mosasaur from the Upper Cretaceous of
the Netherlands. Netherlands Journal of Geosciences; vol. 81. (possible the
best ref. Is in English, so it is much easier to read for the majority on
this list)

- Reportage, Natuur & Techniek, maart 2002: pag. 86-89. (in Dutch)

- Maatrichtien, Natuur & Techniek, oktober 1999: pag. 78-85. (in Dutch)

On the web:

Natuurhistorisch Museum Maastricht
www.nhmmaastricht.nl

Known material:

Incomplete skeleton including a skull with complete lower jaw lacking the
premaxilla, nasal and a few teeth. The remainder of the specimen includes 21
preserved presacral vertebrae (a nearly complete neck and most of the
posterior verts) and 16 caudal vertebrae (both proximal and distal caudals),
a scapula and coracoid, a radius  and a digit from the thumb (third)

The skeleton of Prognathodon saturator was fairly messed up as it became
clear during the excavations in the spring of 1999. The scapula was about 8
metres removed from the skull, the flippers and large parts of the tail were
missing and the back was lain in a stronge corned compared to the neck. Once
the carcass had drifted to the bottom of the ocean, it was ripped apart by
scavengers. The presence of teeth of the shark genera Squalicorax and
Plicatoscyllium enhanced this view of the postdepositional processes.
Sharks change their teeth all the time; when eating, with some regularity,
they will fall out of the jaw of the shark. The large Squalicorax sharks did
most the damage is believed by being the first ones there and eating and
ripping most of the carcass apart. The much smaller Plicatoscyllium sharks
finished the job.  The numerous marks left by the teeth on the bones of P.
saturator in different parts of the skeleton are still well visible.

A cladistic analysis was done and from this analysis resulted that this
animal clustered with the mosasaurs from the genus Protognathodon. Typical
features of Prognathodon include the heavily built, curved lower jaw and the
relatively large teeth in the pteryoid bone. This specimen (nicknamed "Bèr")
differed in a number of features from the than known Prognathodon-species,
which resulted in the description of the new species. Despite the
differences in morphology are the measurements of Bèr relatively unusual for
Prognathodon. With a jaw lenght of 1,43 metres is Bèr's skull larger than
the skull of Prognathodon giganteus. Unfortunately, no complete skeleton is
known for P. saturator. Earlier published guesses about the ratio between
skull and body lenght varied between 10% and 14%. A lenght longer than 14
metres would not have been possible. Mike Everhart suggested early februari,
based on measurements from closely related American mosasaurs, a lenght of
11 or 12 metres would be more accurate. With this data, it makes P.
saturator not one of the longest mosasaurs, but it does make it one of the
heaviest.

Cheers,

Rutger Jansma