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Tom
Holtz recently (IHHO in his humble opinion) listed ideas on hot to confirm a
theropods arboreality. These are good ideas. One I think once done and shown
theropods could have climbed trees would then require even more tests and ideas
and so on and so on because of the terrestriality bias. What needs to be done
is to stop Pigeon hole nature into arboreality, but nature will prove us wrong. There
has been a recent study on island endemic lizards (I didn’t copy the article
but I know the series that it was in. I wish I had copied it.) showed that
terrestrial and arboreal lizards of the same genus (?, or was it species?) did
not show any skeletal differences. If it was found in a quarry it would have
been interpreted as being terrestrial. Komodo monitors will climb trees until
it reaches a length of 6 feet. They also show arboreality in their skeletons.
Bears climb, a certain goat can climb trees, dogs, squirrels, etc, but their
skeletons don’t show this. What about the pelycosaurs _Varanosaurus_ and _Aerosaurus_? They are about the size of a small Komodo monitor, could
they climb trees? With
theropods there is a terrestrial bias, and placing a theropod in a tree gets
laughed at. I’ll admit that I was one who laughed at the idea. Greg Paul had
put on _Ornitholestes_ in a tree
and I thought yea right. But maybe he’s right. I’ll have to look at it more
closely. What about dromaeosaurids? Could they have climbed trees? This is
something I’m working on and a few others. Will that be accepted? Probably not.
A _Deinonychus_ is bigger than a
Komodo monitor but would have been lighter. Why must theropods be put through a
more rigorous testing than other animals? Terrestrial bias is why. There
are some animals that arboreality is not questioned. _Kuehneosaurus, Icarosaurus, Coelurosauravus_ with there long ribs are
believed to have been gliders so it had to climb trees to have something to
glide from. No big tests needed. There
is a preconceived notion on what an early bird would look like. But when one is
found in the Late Triassic it is considered to be a composite because it
doesn’t fit that preconceived notion. I’ve talked to Sanker and the person who
excavated _Protavis_.
I believe them that it is just one genus in the block. I bet even if a totally
intact, articulated specimen, it will still be thought of as a composite
animal. The
opposite is true for _Rahonavis_.
It is a long tailed bird that is older than Archaeopteryx. Some believe that
this is a composite animal. With the bird_Vorona_ and a theropod. There are three reasons
why this is wrong. 1). The _Vorona_
is two big for _Rahonavis_
arms. 2). There is a sauropod skeleton in between the two and most importantly _Vorona_ is from a lower bedding
plain. There were long tailed birds in the Mesozoic, but since they do not fit
the idea of a bird, then it is considered to be a composite. Just because the
animal doesn’t fit a preconceived notion doesn’t mean it is a composite. Trees
are a niche that was filled and it should be considered. What
about burrowing animals? We know _Thrinaxodon_
and _Cistecephalus_ were burrowers
because they were found in burrows. Bakker says Drinker was found in a burrow,
but does anyone believe him? Not many, because he’s Bakker. There are some
things that Bakker says that I disagree with, but this I think he may be right.
Also _Protoceratops_ is now
considered by a few to have been a burrower. Just because Bakker says it
doesn’t mean that we should just dismiss it. So there were niches during the Mesozoic
that was filled, in trees and in the ground, that needs to be thought about and
not forgotten. Just because an animal doesn’t fit a preconceived notion, it
doesn’t mean that it is a composite. We need to have a more open mind for what
animals could have done. Tracy |