STL Science Center

STL Science Center

07 December 2012

Father of the Family

It is not often that we have a head of the family with a week dedicated to them. This week, however, is different from other weeks. Instead of tackling a species whose name appears only at the generic level we are tackling one that has an entire family, and subfamily, named after it. It appears as follows taxonomically (I simplified it a little):

Bonaparte & Novas, 1985
Bonaparte & Novas, 1985
† A. comahuensis

As we can all see the dinosaur in question this week is Abelisaurus. Abelisaurus is, somewhat obviously I think, characteristic of the Abelisaurids in specific areas. These characteristics are mostly found in the skull, as that is the only known material; the skull shares many characteristics, though not diagnostic characters, of the Tyrannosaurs. The skull possesses rugosities which may have once supported keratin hornlets along the nasal and supratemporal horns are probably. The skull itself bears many resemblances to Carnotaurus and indicates that the two were fairly closely related. The lack of post cranial skeleton, however, makes it difficult to ascertain total length, skull estimates of 85cm in length indicate a body length from 7 to 9 meters (25-30 feet) making it a rather large theropod of South America, and the posture of the body. Many Abelisaurids are known to have reduced forelimbs, another trait reminiscent of Tyrannosaurs, which are often held facing posteriorly (that is rearwards in layman terms) with the palms against the ribcage. Abelisaurus, though, not having forelimbs associated with its remains, is a bit of a mystery in the posturing of its forelimbs, and as such it is not known if it conforms to this behavior. Knowing that information could shift the placement of Abelisaurus within its own family, a topic which we will discuss in the coming days.

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