Friday, June 26, 2015

Primitive birds - Quick summary

There were pennaceous-feathered, long-bony-tailed primitive birds.
The most basal were flying (eg. scansoriopterygids, tetrapterygids).
Some later ones became secondarily flightless (eg. oviraptors, eudromaeosaurids etc).

These primitive birds have a great deal in common with pterosaurs. They evolved from pterosaurs.
These primitive birds have almost nothing in common with dinosaurs.


Oviraptor (secondarily flightless)

Monday, June 22, 2015

Oviraptor Propatagium

More evidence that oviraptors were secondarily flightless and not transitional between dinosaurs and Paraves.,d.aWw
Testing the neoflightless hypothesis: propatagium reveals flying ancestry of oviraptorosaurs (2015)
Alan Feduccia1• Stephen A. Czerkas2
Considerable debate surrounds the numerous
avian-like traits in core maniraptorans (oviraptorosaurs,
troodontids, and dromaeosaurs), especially in the
Chinese Early Cretaceous oviraptorosaur Caudipteryx,
which preserves modern avian pennaceous primary remiges
attached to the manus, as is the case in modern birds.
Was Caudipteryx derived from earth-bound theropod dinosaurs,
which is the predominant view among palaeontologists,
or was it secondarily flightless, with volant avians
or theropods as ancestors (the neoflightless hypothesis),
which is another popular, but minority view. The discovery
here of an aerodynamic propatagium in several specimens
provides new evidence that Caudipteryx (and hence oviraptorosaurs)
represent secondarily derived flightless
ground dwellers, whether of theropod or avian affinity
that their presence and radiation during the Cretaceous may
have been a factor in the apparent scarcity of many other
large flightless birds during that period.
There is actually no link between dinosaurs and Paraves.

See here for more details about oviraptors as secondarily flightless:

Friday, June 5, 2015

Dinosaurs are not similar to primitive birds

The following study shows that there were 51 synapomorphies (unique defining characteristics) for Paraves (primitive birds). This means that of the 374 characteristics that were evaluated, 51 of them were different than the claimed dinosaur ancestor. This is more than 1 in 8. This means that primitive birds are not similar to dinosaurs, which is a point that I have being making for a very long time. It is good to see a cladistic analysis confirm this point. 
Note that this number would be very much larger if the oviraptors etc were taken as secondarily flightless.

2011 study (Xu et al):
 An Archaeopteryx-like theropod [Xiaotingia] from China and the origin of Avialae
Here we report a new Archaeopteryx-like theropod from China. This find further demonstrates that many features formerly regarded as being diagnostic of Avialae, including long and robust forelimbs, actually characterize the more inclusive group Paraves (composed of the avialans and the deinonychosaurs). 
Paraves: 1.1, 10.1, 13.0, 14.0, 15.1, 20.1, 21.1, 28.1, 39.0, 61.1, 65.0, 66.0, 69.0, 79.0, 91.0,95.0, 96.1, 97.1, 106.0, 109.1, 119.1, 125.0, 127.1, 129.1, 137.1, 138.1, 139.1, 154.0, 155.1,156.1, 160.1, 166.0, 176.1, 179.1, 180.1, 184.1, 202.1, 221.1, 232.0, 237.1, 262.1, 267.1,277.2, 292.0, 304.2, 306.1, 319.1, 320.2, 336.1, 354.0, and 362.1