Saturday, January 24, 2009

Lesothosaurus

Among the first true dinosaurs, lesothosaurus is considered an ancestor of the entire subsequent class of ornithischian (bird-hipped) dinosaurs, and was perhaps one of the first predatory dinosaurs from which all the great meat eaters developed. Although it was only the size of a modern house cat, this strange animal's teeth are almost like those of modern mammals: with pointed teeth at the front of the mouth which suggest that this creature may have eaten meat from time to time.

Lesotho is a remote, mountainous region in southern Africa, where fossilized remains of this dinosaur were first discovered in 1978. Lesothosaurus remains have also been found in South America, which was connected to Africa's west coast at the time. Because of its hot, dry conditions in an area relatively unmolested by man, Lesotho has been a valuable source for dinosaur hunters.

Lesothosaurus is very similar to the previously discovered fabrosaurus. In fact many scientists believe the two were actually the same animal. Remains of fabrosaurus, however, are so poor that it is impossible to say for sure.

Lesothosaurus had hollow bones and a small, light skeleton. Its only defense against a large predator would have been its ability to run away quickly, similar to the behavior of modern gazelles.

This animal shares many features with other ornithischian dinosaurs in addition to the bird-like hipbones. A "predentary" bone links the left and right sides of the lower jaw together. This bone was covered with a horny sheath, giving the animal a beak shaped mouth without the fleshy cheeks of most meat eaters. It also had a bone across its eye and eye socket, similar to those found in modern crocodiles.

It is interesting to note that, although it lived 208-200 milliuon years ago, ages before the first mammals, lesothosaurus had five digits on each hand and five toes on each foot.

For a long time, lesothosaurus was considered a very early ornithischian, related to hadrosaurs (duck-billed dinosaurs) and hypsilophodon. These animals were seperated from each other by more than 80 million years, however, leading one to believe that lesothosaurus actually has no close relative known to modern science. For this reason, it is difficult to classify on the dinosaur family tree.

Was lesothosaurus the mother of all carnivorous dinosaurs, or is the resemblance simply a coincidence?

For my previous posts on dinosaurs, click here.

Check out a couple good books on dinosaurs in the Hansisgreat Gift Shop. My two favorites are National Geographic Dinosaurs, by Paul Barrett; and Dinosaurus, by Steve Parker.

5 comments:

steve said...

lesothosaurus!

Ah, the sweet, sweet music of Hans is Great, playing once again!

Al said...

One correction: saurischians, not ornithischians, are considered to be the ancestors of modern birds.

I love your site and the mix of brain food with eye candy. Welcome back, & please keep it up!

Hansisgreat said...

Oops. You are, of course, correct about saurischians and birds. I even knew that, but still made the mistake. It's quite counter-intuitive, that birds are closer relatives to lizard-hipped dinosaurs than bird-hipped. Thanks for pointing out my error, it was fixed in the post.

And thanks for the lovely compliments, Steve and Al. You've made me blush!

C. said...

I don't know if you can read French at all, but there's a book which has just been released here (probably not translated into English if it ever is) :
Pascal Picq, Darwin et l'évolution expliqués à nos petits-enfants (Darwin and evolution explained to our grand-children), Paris, 2009 [ISBN. 978.2.02.099061.5].

It's a popularisation book dealing with evolution: its history, philosophy, opposition to fixism/creationism and aims.
It's written like a regular conversation between a scholar and someone who doesn't know much about the subject.

The author is a paleoanthropology teacher at the "Collège de France".

Thanks for enlightening us both with your well documented articles and the eyes candies :)

Hansisgreat said...

Je regrette de ne pas lire ou parler le français. Je peux utiliser Google Translate, though.
Merci pour le commentaire et pour le livre suggestion.