Friday, June 12, 2015

Understanding Dinosaurs - Part 5: Saurischian Dinosaurs - Therapods

The second suborder of Sauruschian dinosaurs are called the Therapods (which means 'beast foot'). The creatures of this grouping are largely carnivores, though a few later animals were not. Most therapods possessed significantly shorter forelimbs leading to most of this group to be bipedal (walked on two feet). This is the group we mostly think of when we think of carnivorous dinosaurs, or bird-like dinosaurs. In fact, modern birds are now actually considered part of the therapod suborder (more on that in bit).

I'd like to be able to break down the therapods as easily and cleanly as I did with the previous groups, but it really wouldn't do the group justice. The suborder consists of numerous infraorders, divisions, and subdivisions. The best I can do is to direct you to look at more detailed dinosaur classification charts. These charts can better fit these groups into the Linnaean system (though it gets a lot more complex than the simple version of the system we have previously discussed).
Instead, let's look at some of the most iconic groups and subgroups.

The Abelisauroids were once a very successful group of carnivores. This group included the tiny armed hunters, the Carnotaurs (who were an enjoyable enemy in my beloved animated classic Disney's Dinosaur (2000)). The Abelisauroids we most prevalent on the southern continents, possibly due to the more successful carnivores of the north, such as T. rex. This subdivision of the larger Ceratosauria infraorder was named after the Abelisaurus (the larger head in the above illustration).

This group contains dinosaurs such Megalosaurus, Torvosaurus, and the Spinosaurid family. The Spinosaurids were unique piscivorous (fish-eating) dinosaurs. My personal favourite dinosaur Baryonyx resides within this family, alongside its enormous cousin Spinosaurus. Scientists are still learning a lot about Spinosaurus (once featured in Jurassic Park 3), and have recently found that all their best guesses about Spinosaurus were previously quite wrong. The specimens and research of this dinosaur make up an interesting story in their own right (which I won't go into here, but I highly recommend looking into it. Check out part 10 of this series for more resources and suggestions).

Carnosaurs (apart from being the antagonist of a fantastically cheesy horror novel and film series), once contained a wide variety of therapods, but it has since been thinned down to pretty much only contain Allosauroids. Allosaurus is considered by many to be the most successful carnivorous dinosaur that ever lived. We certainly find more of its fossils than any other. It is also very well known to us, here in North America, because this is where it once roamed over 150 million years ago. There is a staggering amount of information out there about this one species alone.

This clade of therapods contains all the therapods that appear more closely related to modern birds than to Carnosaurs. It contains everything from the tiny Compsognathids to the giant Tyrannosauroids. Most distinct among this group are the ornithomimosaurs('bird-mimics', such as the ostrich like Gallimimus) and the Maniraptora (deadly hunters such as Deinonychus and Velociraptor). And at the end of all the branches of the Coelurosauria is a small class of animals that we all know too well, Aves (modern birds). That's right, birds are the only remaining group of dinosaurs on the planet. Want to know more about the connection between birds and dinosaurs? Check out the next post in the series...

Next time: Part 6 - The Bird Connection


Megan Powers said...


Megan Powers said...
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