[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: [dinosaur] Fossil theropods, dated phylogenies: topology, divergence dates, and macroevolutionary inferences

Honest-to-goodness, nothing has changed in that aspect. Some modern phylogeneticists can pretend that they can ID ancestors with varying degree of certainty, but in actual reality they can't. An algorithm is all well and good, but they have no independent empirical evidence to back up their conclusions.
Furthermore, except for a theropod specialist (and indeed, to MANY of us), there is no difference between Archaeopteryx & Wellnhoferia! (Or at least, no confirmation that it lies outside the set of specimens otherwise called "Archaeopteryx"). This is the danger of skilled phylogeneticists who are not actually familiar with the specimens, or indeed the taxonomy and taxonomic history, of a field.
This is a good paper for what it is about, namely showing the difference between different software packages and algorithms within them in trying to assess the same question. But please don't go to this for details on theropod systematics! 

On 2016-07-14 17:32, David Černý wrote:

A comment from the lead author:


My favorite line from the paper is this:
"While Archaeopteryx is popularly referred to as an ‘ancestral
bird’, it is a sampled ancestor in only 5% of the MrBayes
posterior (0% for BEAST2 SA), and then only to its close relative
Wellnhoferia, not the more nested Avialae."







Read over it again and think about the last time you ever heard of
anyone quantifying the statistical support that something was a
sampled ancestor or not. Brave new world!


This certainly goes to show just how far paleo-phylogenetics has come
in the thirty years following Gauthier's (1986: 12) assertions that
"[h]ypotheses of ancestral status can only be weakly supported in that
they are based on negative evidence" and that "there is no unequivocal
evidence supporting the alternative hypothesis, that _Archaeopteryx_*
is monophyletic and thus not an ancestral bird."

REF:

Gauthier JA 1986 Saurischian monophyly and the origin of birds. Mem
Calif Acad Sci 8: 1–55

--
David Černý


--
Thomas R. Holtz, Jr.
Email: tholtz@umd.edu         Phone: 301-405-4084
Senior Lecturer, Vertebrate Paleontology
Office: Geology 4106, 8000 Regents Dr., College Park MD 20742
Dept. of Geology, University of Maryland
https://urldefense.proofpoint.com/v2/url?u=http-3A__www.geol.umd.edu_-7Etholtz_&d=DQIDaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=k0zuT7g5Q9I9F4w-1-CqyJvcmpvP0Xn6N99lQD3kUpI&s=f1SkhreyZbtBe33kChZNuZOsz5J2qY5H4R0-_B6zHIg&e= Phone: 301-405-6965 
Fax: 301-314-9661

Faculty Director, Science & Global Change Program, College Park Scholars
Office: Centreville 1216, 4243 Valley Dr., College Park MD 20742
https://urldefense.proofpoint.com/v2/url?u=http-3A__www.geol.umd.edu_sgc&d=DQIDaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=k0zuT7g5Q9I9F4w-1-CqyJvcmpvP0Xn6N99lQD3kUpI&s=9-bF-OEj4-Yie2tflUL0h39DTYYlsdngk1APzufHfTQ&e= Fax: 301-314-9843 

Mailing Address:
Thomas R. Holtz, Jr.
Department of Geology
8000 Regents Drive
University of Maryland
College Park, MD 20742