PISANOSAURUS

[Tetanurae@aol.com]

Philidor11@aol.com wrote:
<< All I had about pisanosaurus was (Norman again, tho other books have
similar
 statements): The earliest ornithopod (possibly a heterodontosaurid) is
claimed to be  
 an animal named pasanosaurus [sic]...from the late triassic of Argentina.
However,
 the very fragmentary remains of this animal do not make it clear even if it
is an
 ornithischian, let alone an ornithopod, so we should perhaps note the
 existence of this fossil and hope that more material is discovered that will
 prove exactly what sort of animal this is.>>

There is not much known of Pisanosaurus, what is known shows it is a very
basal ornithischian.  It was not a heterodontosaurid because it didn't have
the fangs, and also had none of the other specializations of heterodontosaurs.

Additionally, it had a very primitive ankle, and what is known of the pelvis
suggests it was propubic, like saurischians.
 
 <<The section (Fabrosaurids & Heterodontosaurids) goes on to discuss
 lesothosaurus australis approvingly.  This dates from the upper triassic and
 that brings them in range of the anchisaurs.>>

This was a big mistake on Norman's part.  Fabrosaurus australis was based on a
partial jaw with teeth which is indeterminate specifically (though Tony
Thulborn who's on and off the list disagrees with me).  Lesothosaurus
diagnosticus is based on the excelent complete skeletons described by Thulborn
in the 70's as Fabrosaurus.  There is no such thing as Lesothosaurus
australis.  Additionally, all these specimens come from the earliest Jurassic,
and not the Triassic.

Some other Triassic ornithischians are Technosaurus from Texas, and a variety
of tooth taxa named by Hunt and Lucas.

You might want to check out:

Bonaparte, J F.  1976.  Pisanosaurus mertii Casamiquela and the origin of the
Ornithischia.  Journal of Paleontology 50:808-820.

Chatterjee, S.  1984.  A new ornithischian dinosaur from the Triassic of
Texas.  Naturwissenschaften 71:630-631.  (describes the fragmentary
Technosaurus smalli, an ornithischian from the Triassic)

Hunt, A P, and Lucas, S G.  1994.  Ornithischian dinosaurs from the Upper
Triassic of the United States.  In: In the Shadow of the Dinosaurs: Early
Mesozoic Tetrapods, Fraser, N C, and Sues, H-D (eds).  Cambridge University
Press, 227-241.

Padian, K.  1990.  The ornithischian form genus Revueltosaurus from the
petrified forest of Arizona (Late Triassic: Norian; Chinle Formation).
Journal of Vertebrate Paleontology 10(2):2687-269.

Peng, G-Zh.  1997.  Fabrosauridae.  In: The Dinosaur Encyclopedia, Currie, P J
and Padian (eds).  Academic Press, 237-240.

Sereno, P C.  1991.  Lesothosaurus, "fabrosaurids," and the early evolution of
the Ornithischia.  Journal of Vertebrate Paleontology 11(2):168-197.

Thulborn, R A.  1970.  The skull of Fabrosaurus australis, a Triassic
ornithischian dinosaur.  Palaeontology 13(3):414-432.

Thulborn, R A.  1972.  The post-cranial skeleton of the Triassic ornithischian
dinosaur Fabrosaurus australis.  Palaeontology 15(1):29-60.

Thulborn, R A.  1992.  Taxonomic characters of Fabrosaurus australis, an
ornithischian dinosaur from the Lower Jurassic of Southern Africa.  Geobios
25(2):283-292.

Peter Buchholz
Tetanurae@aol.com