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Re: getting a handle on Dinosaur taxonomy



To really be scientifically answerable, I think you need to quantify these
questions better. You could couch it in terms of breeding: "Would
_Daspletosaurus_ be able to interbreed with _Albertosaurus_?" (Answer: Well, we
haven't found any hybrids ... but it's conceivable.) Or in terms of divergence
dates: "When did coelurosaurs diverge from carnosaurs?" (Answer: By the Late
Jurassic.) Or in terms of time between two taxa and their last common ancestor:
"How long were the lineages of _Triceratops_ and _Leptoceratops_ (two
contemporaries) separate from each other?" (Answer: From before the Albian up
to the late Maastrichtian; over 35 million years.)

Remember that ranks like "genus", "class", "order", etc. (and arguably
"species" as well) are really more indicators of tradition that of any
scientifically confirmable facts.

More notes below:

--- Eric Martichuski <herewiss13@hotmail.com> wrote:

> I'm having a hard time wrapping my brain around the relationships between 
> dinosaurs, and I was hoping someone might be able to clarify matters in 
> terms of modern species comparisons.
> 
> When we talk about two different hadrosaur species, would it be like 
> comparing two antelope?  Or do you need to go further out to a comparison 
> between all two-toed hoofed mammals.  Or is it just the variation between 
> mule deer and white-tailed deer?
> 
> Are T. Rex and some other large contemporary theropod carnivore (I'm 
> blanking on names) like Lions and Tigers?  Indian and African Lions?  Or 
> more like Bears and Wolverines?
> 
> I realize the question covers a _lot_ of complicated ground, but I'm just 
> trying to get a simple handle on the issue by analogy.  Most paleontology 
> seems to deal with relationships by evolutionary descent (species x begat 
> species y which begat species z) rather than looking at the separation 
> between contemporaries.

Actually, this is no longer the case. Since ancestry is essentially unprovable,
systematists are more interested in finding branching patterns than in finding
ancestors nowadays.

> You've got two ceratopsians.  Do I look at them 
> like Moose and Elk or like red and grey Foxes?
> 
> I'm probably not helped by ignorance over where larger dinosaur grouping 
> fall in the taxonomic order.  For example: is "Therepod" an order?  A class? 
>   A family?

_Theropoda_ is a clade (an ancestor plus all descendants). Traditionally it was
usually an infraorder, but, again, this doesn't mean anything of scientific
value.

There are very detailed diagrams of phylogenetic relationships between dinosaur
"genera" on the old version of my site, The Dinosauricon, at
http://dinosauricon.com; they are a few years out of date, but still relevant
in most respects.


=====
=====> T. Michael Keesey <http://dino.lm.com/contact>
=====> The Dinosauricon <http://dinosauricon.com>
=====> Instant Messenger <Ric Blayze>
=====


                
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