Re: Velociraptor Footprints( Arundel contemporary)

[Tompaleo@aol.com]

In a message dated 97-08-24 19:44:44 EDT, you write:

<< We can imagine out 'raptors dropping off occasionally for a spot of
 >unsuspecting lunch - perhaps protoceratops.  This behaviour is not
 >entirely without analogs.  Egrets, secretary birds and many other
 >species ride large herbivore "platforms" in a similar way, using them 
 >to
 >spot and flush out prey.  
 
 But we still get good tracks from egrets, secretary birds, oxpeckers,
 etc.  The modern birds you mention don't spend all their time on these
 living platforms, and neither would the dromaeosaurs.  
 
 Is this why some quadrupedal dinosaurs developed armored backs?  ;-)
  >>
Damn good question! Which has set off yet another light!  

Actually, I have been meaning to update my Md. Dino Web page  with something
along this line but I have not had the time to do so...

I've been pondering a  problem that has been plaguing me for some years now.
The Nodosaur, _Priconodon_crassus_, was described by Marsh (1888) from the
Arundel Formation. It is mostly known from it's leaf shaped teeth (crowns)
and some postcrania AFIK figured by Lull (1911). In 8 years of work, I have
only found these same teeth in all states of wear and  weathering and one or
two possible verts if Lull's figure is accurate. To date, NO dermal armor or
horns have been reported which has led me to hypothesize that P. crassus was
a _NAKED_ Nodosaur!

Now many of us are aware of the apparent predator-prey relationship that
existed between Deinonychus and Tenontosaurus from stratigraphically,
temporally  equivalent beds in Wyoming and Montana (Cloverly Fm.) and most
recently reported in Oklahoma (Antlers Fm.) by Brinkman et al 1997. On my
recent visit to Ok, I attended a dig where a previous crew had uncovered a
single dorsal vertebra( but possibly part of a series that projected
vertically down into the ground) of a Tentosaur with associated ossified
tendon, several tenonto dentaries and 3 Deinonychus teeth! 

Well to make a long story short, there is no evidence of Tenontosaurus sp. in
the Arundel. Recently  two teeth have been recoovered ( one by P. Kranz in
1990 the other by me this year) indicate the presence of a new ornithopod
dino that tantalizingly bore _some_ resemblance of Tenonto. Unfortunately,
these two teeth also have slight resembalnce to Ceratopsians and
Hypsylophodonts as well, according to some experts I have spoken with who
also practically  rule out tenonto.

But I digress...

I have yet to publish anything on the following but it is in the works. 

There is most certainly, based on teeth ( shed crowns), the presence of a
dromaeosaur, probably Deinonychus in the Arundel Fm, of Maryland which pushes
the occurrence of this critter all the way to the east coast of the US! I
have a substantial collection of shed and possibly partially digested teeth
diagnostic of this genus.  But no Tenontosaurs!

Back to my naked Nodosaur. Judy, your question reignited a hypoythesis I had
been toying around with for some time. It seems possible, based on the
evidence available to me at this time, that 1) P. Crassus was a naked
nodosaur and,  2) A dromaeosaur , possibly Deinonychus, may have fed on it. 

With the added presence of an almost certain, _Acrocanthosaur_ and possibly
one other large Coelurosaur (sensu Holtz) ,this poor nodosaur must have had
one rough time of things which could help explain why so little material has
made it into the fossil record and why so little is known about it ( In _The_
Dinosauria_, P. crassus is listed as a nomen dubium). There is also, the
taphonomic problem. The Arundel was most probably a series of Oxbow lake
 deposits, ie. acidic, boggy and anoxic,  and it is quite possible that
disssolution of bone was intense. I hope to answer this and many other
questions as my work progresses. 

How big was P. crassus? I do not know. Mike Brett-Surman once told me that if
a complete tooth crown and root were recoverd, it is theoretically possible
to scale the skull up and thus project the bodys possible size. Luckily, this
past June, I found just such a specimen which is over 4.5 cm long ( another
Arundel first)! Now I need only to crunch the numbers. Does anyone out there
know the formula?

Just imagine, a group of Deinonychids pouncing on the back of an unfortunate
naked  nodosaur. Such a predator -prey relationship may have helped select
for dermal armor!

Regards,

Thomas R. Lipka
Paleontological/Geological Studies
http://members.aol.com/Tompaleo/Maryland.Dinosaurs.html


PS,

The typos  nd omissions in this and all posts are completely those of my
keyboard and do not reflect the state of the author!