Saturday, January 14, 2017

Studies

The following study shows that there were 51 synapomorphies (unique defining characteristics) for Paraves (long-bony-tailed primitive birds). This means that of the 374 characteristics that were evaluated, 51 of them were different than the claimed dinosaur ancestor. This is a more than 1 in 8 saltation. This means that Paraves 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 is very much larger when the oviraptors are taken as secondarily flightless.

2011 study (Xu et al):
http://www.nature.com/nature/journal/v475/n7357/full/nature10288.html
http://www.ivpp.cas.cn/qt/papers/201403/P020140314389417822583.pdf
An Archaeopteryx-like theropod from China and the origin of Avialae
Archaeopteryx is widely accepted as being the most basal bird, and accordingly it is regarded as central to understanding avialan origins; however, recent discoveries of derived maniraptorans have weakened the avialan status of Archaeopteryx. 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). Notably, adding the new taxon into a comprehensive phylogenetic analysis shifts Archaeopteryx to the Deinonychosauria. Despite only tentative statistical support, this result challenges the centrality ofArchaeopteryx in the transition to birds. If this new phylogenetic hypothesis can be confirmed by further investigation, current assumptions regarding the avialan ancestral condition will need to be re-evaluated. (Characters 1-363 are from Hu et al. (2009), whereas 364-374 are newly added). 
Unambiguous synapomorphies for selected coelurosaurian clades:  
Deinonychosauria: 29.1, 72.1, 75.1, 82.0, 111.1, 134.1, 171.2, 183.1, 189.0, 199.1, 233.1, 238.0, 255.0, 294.1, 297.1, 302.1, 323.1, 334.1, 335.2, 359.0, 364.0, 365.0, 366.1, 367.0, 368.0, 371.0, and 372.1 
Paraves (51):
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
Paraves-Oviraptorosauria-Therizinosauroidea (41):
13.1, 14.1, 28.0, 29.0, 39.1, 41.2, 54.0, 66.2, 79.1, 91.2, 106.1, 116.1, 117.1, 119.0, 121.1, 125.1, 126.1, 127.0, 130.1, 131.1, 136.1, 144.1, 157.2, 166.2, 167.2, 200.1, 238.1, 255.1, 276.1, 284.1, 300.1, 329.1, 351.1, 354.1, 359.1, 363.1, 364.1, 365.1, 367.1, 368.1, and 371.1.
AND ALSO:
Some other suggested synapomorphies are present in recently described basal deinonychosaurs, and are thus likely to represent paravian rather than avialan synapomorphies23,37. These features include an antorbital fossa that is dorsally bordered by the nasal and lacrimal, a relatively small number of caudal vertebrae, a relatively large proximodorsal process of the ischium, a relatively long pre-acetabular process of the ilium, and fusion of the proximal part of the metatarsus11,37,41

2009 study (Hu, D.Y. et al)https://www.ncbi.nlm.nih.gov/pubmed/19794491
http://www.nature.com/nature/journal/v461/n7264/extref/nature08322-s1.pdf
A pre-Archaeopteryx troodontid from China with long feathers on the metatarsus. Nature 461, 640-643

2008 study (Zhang)
www.ivpp.ac.cn/qt/papers/201206/P020120601535055482173.pdf
http://www.nature.com/nature/journal/v455/n7216/suppinfo/nature07447.html
A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers
Characters 361-363 are newly added. Characters 4, 25, 33, 40-42, 65, 67, 69, 82, 85, 91,
99, 106, 110, 115, 116, 121, 122, 136, 138, 142, 146, 148, 151, 153, 163, 165-167,
169, 171, 178, 181, 200-203, 212, 230-360 are from Senter (2007); others are from
Kirkland et al. (2005).
http://www.nature.com/nature/journal/v435/n7038/abs/nature03468.html
Kirkland, J. I., Zanno, L. E., Sampson, S. D., Clark, J.M. & DeBlieux, D. D. 2005.
A primitive therizinosauroid dinosaur from the Early Cretaceous of Utah. Nature 435: 84–87.
Characters 1-222 based on Norell et al. (2001, with references) from Hwang et al. (2004).

http://peabody.yale.edu/scientific-publications/new-perspectives-origin-and-early-evolution-birds
http://peabody.yale.edu/sites/default/files/documents/scientific-publications/Norell.pdf
Norell, M.A., Clark, J.M., & Makovicky, P.J. 
Phylogenetic relationships among the coelurosaurian theropods, in New Perspectives on the Origin and Early Evolution of Birds (eds. Gauthier, J. & Gall, L.F.) 49-67 (Peabody Museum of Natural History, New Haven, 2001)


2 comments:

  1. https://academic.oup.com/icb/article/40/4/504/101454/Origin-of-Birds-The-Final-Solution-1
    Peter Dodson
    The search for the ancestry of birds is a real evolutionary problem. In the 19th century, one could take the position that the fossil record was too incompletely known to constrain the time of origin of birds or of any major group (Huxley sought the origin of birds in the Triassic or earlier (Huxley, 1868; indeed he sought the ancestors of mammals in the Silurian!—Desmond, 1982). Today the fossil record strongly indicates that there is no credible evidence of birds prior to the Late Jurassic, when Archaeopteryx appeared. There is no evidence of an evolutionary radiation until the Early Cretaceous (Chiappe, 1995; Padian and Chiappe, 1998b), which suggests that the true origin of birds is not to be sought much earlier than that time. In order to understand the ancestry of birds, we seek a method of phylogenetic analysis that can provide us the best possible insights into the real course of evolution. A method that denies in principle the prospect of determining the ancestor and provides us with “hypothetical” ancestors that lived 60 to 80 million years after the event took place does not on the face of it fit our reasonable requirements. It follows that the analysis of the origin of birds is not the closed topic that authors have claimed. How should phylogenetic analysis proceed?

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  2. http://www.sciencedirect.com/science/article/pii/S0960982214010471
    There is growing evidence that changes in discrete character evolution, body size, and limb anatomy occurred quickly in the vicinity of the origin of birds, either at the node Avialae, in close avialan outgroups, or beginning with slightly more derived birds [3, 4, 5, 6, 19, 20, 21 and 22]. It is likely that different types of data will pinpoint changes at slightly different positions on phylogeny, but in general, recent studies converge in identifying the dinosaur-bird transition as an abnormally rapid period of morphological evolution.

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