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Re: Tyrannotitan, new carcharodontosaurid from Argentina



I take it this is not the same as Currie and Coria's long-awaited bonebed carch?

No.

*Tyrannotitan* has an interesting autapomorphy: bilobate denticles on the mesial carinae.

108 characters, 15 taxa (data matrix in supplementary information):
--+--+--*Ceratosaurus*
 |  `--+--*Carnotaurus*
 |     `--+--*Abelisaurus* (not a carch)
 |        `--*Majungatholus*
 `--+--+--*Tyrannosaurus*
    |  `--+--Dromaeosauridae
    |     `--Oviraptoridae
    `--+--*Monolophosaurus*
       `--+--*Sinraptor*
          `--+--+--*Acrocanthosaurus*
             |  `--*Allosaurus*
             `--+--*Tyrannotitan*
                `--+--*Carcharodontosaurus*
                   `--*Giganotosaurus*

*Acrocanthosaurus* and *Allosaurus* have 3 unambiguous synapomorphies, and 9 additional steps are required to make *Ac.* a carch. Too bad *Neovenator* isn't even mentioned.

"*Spinosaurus* B" and *Sigilmassasaurus* are not synonyms of *Carcharodontosaurus*, but they closely resemble each other (or at least one cervical of each does).

"After the strong decline of carcharodontosaurids and the virtual extinction of spinosaurids at the end of the Cenomanian, theropod assemblages from South America, Madagascar and India consisted mainly of comparatively smaller abelisauroids, and secondarily of a wide array of tetanurans (e.g., *Megaraptor*, coelurosaurians)."