Re: Herrerasaurus contemporaries

[Pieter.Depuydt@rug.ac.be]

> Date:          Thu, 19 Jun 1997 13:28:55 -0500
> Reply-to:      j-dyal@geocities.com
> From:          Joshua Dyal <j-dyal@geocities.com>
> To:            dinosaur@usc.edu
> Subject:       Herrerasaurus contemporaries
19 Jun, Joshua Dyal wrote:
> What are some genera that would have been contemporaies of Herrerasaurus
> ischigualensis?  Specifically, what could have preyed on it,
> (rauisuchids like Saurosuchus?) what could it have preyed on, (maybe
> some rhyncosaurs, or dicynodonts?) and what other small predators might
> have competed with it? (maybe Gracilisuchus?)  Any help on the fauna of
> this part of Argentina during Herrerasaurus's time would be appreciated!

<BTW, I saw recently _the Dinosaurs_, a PBS show that included
<interviews with famous paleontologists, and well done animated
<sequences.  In volume three was a short animation about Herrerasaurus,
<and I wondered if anyone could identify the other animals in it. 
<(this is partly what prompted my earlier post about contemporary
<fauna)  I'm guessing the big thecodonian predator was probably
<Saurosuchus, I have no idea what the rhyncosaur should have been, and
<I'm really curious as to what the small burrowing protomammal could
<be.

Herrerasaurus ischigualastensis belongs to the Ischigualasto 
Tetrapod Assemblage, which is Late Triassic (middle Carnian) in age.
This assemblage also contains Eoraptor and Pisanosaurs as early 
dinosaurs (Pisanosaurus however is probably slightly younger than 
Herrerasaurus, I am not sure they were real contemporaries).
As non-dinosaurian archosaurs, there is the giant rauisuchian 
Saurosuchus, which was undoubtedly the top predator of the fauna, the 
large aquatic, crocodile-like, proterochampsid Proterochampsa and the 
herbivorous aetosaur Aetosauroides (the crocodyliform Trialestes is 
found slightly higher in the formation).
(Gracilisuchus you mentioned, is found in the middle Triassic 
(Ladinian) Chanares or Ischichuca formation, so it is older than H.).
Further, there are abundant  rhynchosaurs of the genus  Scaphonyx.
Non-mammalian cynodonts are also well represented, with the large 
genus Exaeretodon and the smaller Ischignathus as abundant herbivores.
Numerous remains of small carnivorous cynodonts have been found: 
these include the recently described Ecteneninion and a new species 
of Probelesodon (species of Probelesodon are also found in the 
aforementioned Chanares formation), and perhaps some Chiniquodon 
material. 
A large herbivore was also the dicynodont Ischigualastia, related to 
Placerias of the US Southwest.
And finally some temnospondyls have been found, 
but I can't give you more details about that.
I have no idea what the burrowing protomammal you saw could have 
been; certainly not the large, pig-like Exaeretodon. Perhaps one of 
the smaller carnivorous eucynodonts?

Regards,

Pieter Depuydt.