Thomas R. Holtz Jr.

Thomas Richard Holtz Jr. (born September 13, 1965) is an American vertebrate palaeontologist, author, and principal lecturer at the University of Maryland's Department of Geology.

[1] He wrote the book Dinosaurs and is the author or co-author of the chapters "Saurischia",[2] "Basal Tetanurae",[3] and "Tyrannosauroidea"[4] in the second edition of The Dinosauria.

The first is the clade Arctometatarsalia, made up of tyrannosauroids, ornithomimosaurs, and troodontids, because all of these coelurosaurs had pinched middle metatarsal bones in their feet.

One of the first scientists to theorize this, Holtz contributed greatly to the debunking of a monophyletic Carnosauria that contained Megalosauroidea, Allosauroidea and Tyrannosauroidea.

However, fellow vertebrate paleontologist Oliver Rauhut is known to recover a monophyletic Carnosauria that contains both Megalosauroidea and Allosauroidea in many of his publications, although like most researcher he agrees that Tyrannosauroids are likely Coelurosaurians as based on the conclusions made by Holtz.