12 April 2013
Tackling Another Tough Opponent
Long time readers know that I enjoy, perhaps even love, taking on difficult cases from time to time around here. This is actually becoming slightly more normal as we get lower in the popularity barrel of dinosaurs. When we first started out the Triceratops and T. rex icons still stood before us and there were vast fields of papers, opinions, models, and other research to draw upon. Then we found our first few "iffy" animals; dinosaurs that were in doubt or, like Monoclonius, had actually been relegated (reassigned) to other genera and referred to other species. This week we shall continue looking at a problem child, in some eyes still despite some positive arguments for the validity of the subject, of the dinosaur world. At approximately 16 feet (4.9m) long and possessing bones that seem to make it drift up and down the family tree of the maniraptorans, this week's dinosaur was called Achillobator giganticus. The animal was named based on the fact that the Achilles' tendon would have been enormous in this animal and the word "bator" in Mongolian means hero. The specific epithet giganticus kind of speaks for itself, I think, in relation to what we will see of it and how it related to other maniraptorans. The trouble that has surrounded this large animal is that the bones, those bones that cause its relationship to winnow up and shimmy down the family tree, are characteristically in many different positions of expected development and this has led to the cry of "CHIMERA!" by some in the paleontology community over the years. During this week we will look over these bones and hopefully by the end of the week (I may need to tweak some of the days' themes to cover everything unique about this animal), we will all be able to form our own thoughts on the validity and perhaps even a generalized relationship of Achillobator with other maniraptorans.