Sunday, June 15, 2008

Monolophosaurus jiangi

Monolophosaurus jiangi is a theropod from the Middle Jurassic of Xinjiang, China. It's phylogenetic position is rather uncertain - though there will be a monograph coming out soon but I can't remember if there was a phylogenetic analysis associated with this redescription.

Of course the most distinctive feature of Monolophosaurus is the large sagittal crest on the skull. The crest is quite thin and has several openings so is probably not a functional structure.

There was some speculation that the basal tyrannosauroid Guanlong wucaii, also from Xinjiang, represents a juvenile morphology of Monolophosaurus. However intriguing this claim may seem, at least one Guanlong specimen shows signs of arrested growth histologically so is quite likely to be an adult.

Here, you see a fine specimen of Monolophosaurus scoping out a carcass.


Zach said...

Good picture, sir! Don't know if I'd call it a sagittal crest, though. Sagittal crests are what the jaw muscles attach to, and tends to be a mammalian trait. When you see a big "ridge" running along the back of the top of a mammal's skull (like a gorilla or a dog), you know that big muscles attach to it. That's the sagittal crest.

The analogous (but maybe not homologous) structure in theropods, anyway, is the half-circle "crest" at the back of the skull, formed by the temporal fenestrae and the top of the braincase. It's especially obvious in Carnotaurus.

Mambo-Bob said...


I used 'sagittal crest' just because it runs along sagittally - I didn't really mean it in the sense of the anatomical terminology.