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Re: new dinosaurs




I wrote:

I have not yet seen the JVP paper (though I would dearly love to), but the cladogram in _Dinosauria II_ shows that _Appalachiosaurus_ and _Dryptosaurus_ come up in different parts of the Tyrannosauroidea tree. The "Alabama taxon" (= _Appalachiosaurus_) belongs on the _Albertosaurus_-_Gorgosaurus_ line of the Tyrannosauridae, whereas _Dryptosaurus_ is given as a basal tyrannosauroid. Any similarities between the two are presumably symplesiomorphic.

Scratch that. According to the JVP paper, both _Dryptosaurus_ and _Appalachosaurus_ are basal tyrannosauroids - though certainly distinct.


THOMAS D. CARR, THOMAS E. WILLIAMSON, AND DAVID R. SCHWIMMER (2005). A new genus and species of tyrannosauroid from the Late Cretaceous (Middle Campanian) Demopolis Formation of Alabama. Journal of Vertebrate Paleontology 25(1): 119-143

ABSTRACT: The discovery of a new genus and species of tyrannosauroid from the Demopolis Formation (middle Campanian) of Alabama increases the known diversity of the clade, although it does not elucidate the place of initial dispersal. This subadult tyrannosauroid is the most complete non-avian theropod collected and described from the Cretaceous of eastern North America. In contrast to tyrannosaurids, the new taxon possesses several plesiomorphic characters, including lacrimals that lack a distinct peaked cornual process, and a dorsoventrally shallow horizontal ramus of the maxilla. Autapomorphies include a wide jugal process of the ectopterygoid, a caudal pneumatic foramen of the palatine that pierces the rostral half of the vomeropterygoid process of the bone, an articular surface for the lacrimal on the palatine that is distally positioned on the dorsolateral process, and pedal unguals that have a distinct proximodorsal lip over the articular surface. Cladistic analysis indicates the new taxon is a basal tyrannosauroid and its presence in eastern North America suggests that the recent common ancestor of Tyrannosauridae probably evolved following the transgression of the Western Interior Seaway. Cladistic analysis indicates that Dryptosaurus aquilunguis is also a basal tyrannosauroid but is less derived than the new genus.