[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Asilisaurus kongwe, the Oldest Avian-line Archosaur and the Early Diversification of Ornithodira
- To: dinosaur mailing list <firstname.lastname@example.org>
- Subject: Re: Asilisaurus kongwe, the Oldest Avian-line Archosaur and the Early Diversification of Ornithodira
- From: David Peters <email@example.com>
- Date: Fri, 5 Mar 2010 07:54:16 -0600
- Authentication-results: msg-ironport0.usc.edu; dkim=neutral (message not signed) header.i=none
- Reply-to: firstname.lastname@example.org
- Sender: owner-DINOSAUR@usc.edu
Okay, the Avian-line problem is understood.
Asilsaurus is Anisian, older than anything dinosaurian and, surprisingly, way
older than Silesaurus.
The dating of the age of the Manda beds >might< be a problem. But maybe not.
The contemporary Xinlingzhen formation produced Lotosaurus, a silesaurid
relative (not tested by Nesbitt's group).
As Nesbitt's group indicate on their temporal chart, the diversification was
earliest Middle Triassic. Probably so. That does leave a long ghost lineage
for dinos. And a long period of not much evolution for Silesaurids.
If Nesbitt's group and others are so keen on keeping pterosaurs with dinosaurs,
why don't they include Cosesaurus (Middle Triassic), Sharovipteryx and
Longisquama (Late Triassic) a couple of very dinosaurian/pterosaurian-looking
And for that matter all the drepanosaurids and Jesairosaurus?
And if Lagerpeton, why not Chanaresuchus and Tropidosuchus (same kind of
pedes)? Surprisingly proterochampsids and phytosaurs often nest just outside
the Ornithodira (don't ask me why).
And then throw in Scleromochlus (a forgotten, in this case, "ornithodiran").
And just to keep things interesting Pseudhesperosuchus, Turfanosuchus,
Trialestes and Gracilisuchus, a couple of bipedal croc-types to see if
bipedalism was shared or convergent?
It gets more interesting the less pre-selection bias is present.