Saturday, November 20, 2010

* Comparing dinos to birds

Many people think that birds evolved from dinosaurs.
To be more precise their claim is that birds evolved from non-maniraptoran coelurosaurs.
And yet when they compare a "dinosaur" to a bird, they do not take a drawing of a non-maniraptor coelurosaurian, (eg. tyrannosaur) but they take a drawing of a non-neornithine Aves (eg. Ichthyornithescreature and compare it with a modern bird.
This of course is irrelevant.
The issue is NOT WITHIN AVES but between non-maniraptor coelurosaurs and maniraptors.

Here are some non-maniraptor coelurosaurs.


These are believed to be sister taxa to the non-maniraptor coelurosaur ancestor of birds. But as we all know, the dino to bird theory enthusiasts never present any pictorial representation of any purported non-maniraptor coelurosaur, bird ancestor.
So who knows what it looks like.

But certainly if we want to understand what the dino to bird theory is actually claiming, we need to compare the non-maniraptor coelurosaurs to modern birds and not non-neornithine Aves creatures to modern birds.

Pterosaur Hand

Here is a great drawing of a pterosaur

It shows the "pteroid bone" which is a neomorph. It shows the other fingers including the extended 4th finger.
It shows that the pterosaurs bent their wings at the junction of the metacarpals and the fingers.
This is different than their descendant modern birds that have fused the hand so they no longer bend at the junction of the metacarpals and the fingers. Instead modern birds bend at the wrist.

Friday, November 19, 2010

Primitive to Modern Birds

Here is a first cut at the development of primitive bird groups to modern bird groups.

See the updated version here:

Friday, November 12, 2010

Prow Beaks

I have been analyzing the pterosaurs to see if they actually had beaks as we use the term "beak". Rhamphorhynchoid stands for "prow beaks". This kind of "beak" is not the extending kind of beak that we associate with the word "beak".
When the pterosaurs evolved into primitive birds, it may well be that the most basal primitive "beakless" birds had snouts, like prow-beaked pterosaurs.
And "beaks", as we use the word, evolved within the primitive birds.
This idea is in line with the fossil record.
This idea requires more analysis but it seems right to me at this point.

Tuesday, November 2, 2010

Protofeathers on the wing membrane

Here is a reference to the "pycnofibres"  - even as early as the Rhamphorhynchus.
If they are  related to feathers they correspond to downy feathers and not pennaceous (contour) feathers.
"The wings were long, and the wing membranes appear to have lacked the furry covering of pycnofibres present in some other pterosaurs (such as Pterorhynchus and Jeholopterus)."
"This type specimen consists of an articulated, nearly-complete skeleton with remains of the integument. These included the wing membrane, hair-like structures, a long version of the vane found at the end of "rhamphorhynchoid" tails, and a head crest with both a low bony base and a large keratin extension"
"The specimen is crushed into a slab and counterslab pair, so that parts of the specimen are preserved on one side of a split stone and some on the other. This includes exquisite preservation of carbonized skin fibers and, arguably, "hair" or "protofeathers." The fibers are preserved around the body of the specimen in a "halo." Wing tissue is preserved, though its extent is debatable, including the exact points of attachment to the legs (or if it attached to the legs at all). In 2009 Alexander Kellner published a study reporting the presence of three layers of fibres [actinofibrils] in the wing, allowing the animal to precisely adapt the wing profile.[3]"

Monday, November 1, 2010

Painten Pelican

Here is a reference to a very interesting picture:
"An unusual pterosaur skull, nicknamed the Painten Pelican, has caused a lot of discussion amongst pterosaur palaeontologists because it is, superficially at least, so danged weird (see image, above). The specimen comprised a complete skull, mandible and cervical vertebra and, if you’re around in Southern Germany, you can see it for yourself: it’s on display in the Solnhofen Museum. A cast and UV photographs of the specimen were making quite a buzz at the 2007 Flugsaurier Meeting, and, apparently, the specimen is very slowly being written up."