Thomas R Holtz, Jr. | |
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| Born | (1965-09-13)September 13, 1965 (age 59) Los Angeles,California, U.S. |
| Education | Johns Hopkins University,Yale University |
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| Known for | Studies of dinosaur phylogeny and Coelurosaurian Tyrannosauroids |
| Scientific career | |
| Fields | Paleontology |
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| Author abbrev. (zoology) | HOLTZ, T.R., JR |
| Website | www |
Thomas Richard Holtz Jr. (born September 13, 1965) is an American vertebratepalaeontologist, author, and principal lecturer at theUniversity of Maryland's Department of Geology. He has published extensively on thephylogeny,morphology,ecomorphology, and locomotion of terrestrial predators, especially ontyrannosaurids and othertheropoddinosaurs.[1] He wrote the bookDinosaurs and is the author or co-author of the chapters "Saurischia",[2] "Basal Tetanurae",[3] and "Tyrannosauroidea"[4] in the second edition ofThe Dinosauria. He has also been consulted as a scientific advisor for theWalking with Dinosaurs BBC series as well as theDiscovery specialWhen Dinosaurs Roamed America, and has appeared in numerous documentaries focused on prehistoric life, such asJurassic Fight Club onHistory andMonsters Resurrected,Dinosaur Revolution andClash of the Dinosaurs on Discovery.[5]
Holtz is also the director of the Science and Global Change Program within theCollege Park Scholars living-learning community at the University of Maryland, College Park.
Holtz was born in California. He has stated that he wanted to be a dinosaur as a child, but upon learning that it is impossible to turn into a dinosaur he shifted his goals to study them. He attendedJohns Hopkins University, where he met his future wife. He then attended Yale, where he metJohn Ostrom, who served as his academic advisor.[6]
Holtz has come up with several new theories and hypotheses about the dinosaurs' classification. For example, he coined the termsManiraptoriformes andArctometatarsus. He also proposed two classification systems for theropods. The first is the cladeArctometatarsalia, made up oftyrannosauroids,ornithomimosaurs, andtroodontids, because all of thesecoelurosaurs had pinched middlemetatarsal bones in their feet. In this proposed classification system, the tyrannosauroids were supposedlybasal to a clade known asBullatosauria, which was made up of theTroodontidae and theOrnithomimosauria. These two groups were purported to form aclade, because they both shared a common characteristic; which was askull capsule. However, later on, both of these classification systems were found to beparaphyletic, or "artificial", clades. For example, troodontids are now known to be deinonychosaurs, or "raptors", closely related to dromaeosaurids and birds. The discovery of basal tyrannosauroids, such asGuanlong, which lacked an arctometatarsus, also helped to disprove this theory. And, eventually, the "skull capsule" in troodontids and ornithomimosaurs was found to be an example ofconvergent evolution, causing the clade Bullatosauria to be abandoned.
Holtz was also a key figure in the discovery that tyrannosauroids were notcarnosaurs, as had been previously believed by most palaeontologists, but rather largecoelurosaurs. One of the first scientists to theorize this, Holtz contributed greatly to the debunking of amonophyletic 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.
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