[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

[no subject]

Date: Wed, 4 Sep 1996 21:14:25 -0400 (EDT)
From: T. Mike Keesey <tmkeesey@wam.umd.edu>
To: mrowe@indiana.edu
Subject: Syntarsus

This message was submitted by "T. Mike Keesey" <tmkeesey@wam.umd.edu> to list
dinosaur@usc.edu. If you forward it back to the list, it will be distributed
without the paragraphs above the dashed line. You may edit the Subject: line
and the text of the message before forwarding it back.

If you edit the messages you receive into a digest, you will need to remove
these paragraphs and the dashed line before mailing the result to the list.
Finally, if you need more information from the author of this message, you
should be able to do so by simply replying to this note.

----------------------- Message requiring your approval ----------------------
Sender: "T. Mike Keesey" <tmkeesey@wam.umd.edu>
Subject: Syntarsus

There's something bothering me about this little predator.

Okay, there are two species - S. kayentakatae and S. rhodesiensis. The
former has paired crests, the latter doesn't. Other members of its family
(Coelophysidae) include Coelophysis (non-crested and small), Liliensternus
(large, crested?), and Dilophosaurus (large and crested). 

It seems like Syntarsus is a paraphyletic species, with S. kayentakatae
closer to Dilophosaurus than to S. rhodesiensis! Is this the case?

Possibly I'm missing something. Did the common ancestor of the
Syntarsus and Dilophosaurus have crests, and then S. rhodesiensis lost
them? Or are the crests a case of convergent evolution?

These two ideas seem less likely to me. Also, someone has recently
suggested to me that Syntarsus was *polyphyletic*, with S. kayentakatae
closer to Dilophosaurus than Liliensternus is to Dilophosaurus
(Liliensternus being closer to these two than S. rhodesiensis).

What's the story here? If it is para/polyphyletic, what happens to the
name? If S. kayentakatae id the type species, I guess S. rhodesiensis
could be sunk into Coelophysis. Otherwise, wouldn't a new name be needed
for S. kayentakatae?

-T. Mike Keesey
Author of the
Dinosaurs and Art and Dinosaur Art