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

Re: Classification of dinosaurs I

>Does anyone have the
>latest classification in a form that could be posted?  Or as a file that
>could be e-mailed?  I realize these things are always in a state of flux, but
>I'm curious to see what some of the latest thinking is regarding dinosaur
>phylogeny (if that's the right term).

There is no consensus yet on all the ingroups of dinosaur phylogeny - in
fact, it is one of the most hotly debated topics of current vertebrate
paleontology.  There are five well established clades (an ancestor and all
of its descendants) recognized in the Dinosauria: Theropoda (bipedal
"carnivores"), Sauropodomorpha (long necked herbivores), Thyreophora
(armored dinosaurs), Ornithopoda (bipedal/quadrupedal herbivores), and
Marginocephalia (dome-heads and frilled ("horned") dinosaurs).  Most agree
that Theropoda and Sauropodomorpha form the clade Saurischia, that
Ornithopoda and Marginocephalia form the clade Cerapoda, and that
Thyreophora and Cerapoda form the clade Ornithischia.  However, every once
and a while people do suggest the existence of Phytodinosauria (=
Ornithischia + Sauropodomorpha).

Below is a preliminary phylogeny of the Dinosauria, based on my own work
and others.  However, some of it is HIGHLY preliminary, and subject to
change with a) new discoveries and b) rigorous cladistic analysis of the
appropriate clades.  I will use "-" instead of spaces in indentation, since
I can't guarentee that the spacing will come out alright.

--Eoraptor (I am not yet convinced this is a theropod, but it does have
some saurischian traits)
---Herrerasauridae (incl. Herrerasaurus, Staurikosaurus)
-----Coelophysoidea (incl. Dilophosaurus, Lilensternus, Coelophysoidea [=
Coelophysis + Syntarsus])
-------Abelisauridae (incl. Abelisaurus, Carnotaurus, ?Majungasaurus,
?Xenotarsosaurus, ?Tarascosaurus, etc.)
-------unnamed group ("advanced megalosauroids")
-------Megalosauridae (incl. Megalosaurus, Torvosaurus, Poekilopleuron, etc.)
-------?Spinosauridae (incl. Spinosaurus, Baryonyx, ?Siamosaurus)
-------Allosauridae (incl. Allosaurus, Saurophagus, Acrocanthosaurus,
Chilantaisaurus, ?Szechuanosaurus)
-------unnamed Wealden "allosaurid"
-------Sinraptoridae (incl. Sinraptor, Yangchuanosaurus, ?Metriacanthosaurus)
----------Dromaeosaurinae (Dromaeosaurus, Utahraptor, Adasaurus, etc.)
----------Velociraptorinae (Velociraptor, Deinonychus)
---------Aves (Avialae sensu Gauthier)
---------Oviraptoridae (incl. Oviraptor, Ingenia, Conchoraptor)
---------Caenagnatidae (incl. Caenagnathus, Caenagnatasia) [?=Elmisauridae]
---------Tyrannosauridae (incl. Tyrannosaurus, Albertosaurus,
Daspletosaurus, Gorgosaurus, etc.)
----------Troodontidae (incl. Troodon, Saurornithoides, Borogovia,
Sinornithoides, etc.)
-----------Ornithomimidae (incl. Ornithomimus, Struthiomimus,
Dromiceiomimus, etc.)
---------?Elmisauridae (incl. Elmisaurus, Chirostenotes) [?=Caenagnathidae]
--Prosauropoda (may be paraphyletic, with some "prosauropods" sharing a
more recent common ancestor with Sauropoda than with others)
[prosauropod systematics are currently pretty fuzzy.  Some groups include
Thecodontosaurus, Anchisaurus, Massospondylus, Plateosauridae,
Vulcanodontidae, etc.  Best check is Galton's chapter in _The Dinosauria_]
---"Cetiosauridae" (almost certainly paraphyletic)
----Neosauropoda [neosauropod systematics here based on smaller cladogram
proposed by Jacobs.  Wilson & Sereno's cladogram is the inverse of this.
Work needs to be done of "cetiosaurids" before this mess is settled!]
------Titanosauridae (incl. Titanosaurus, Aeolosaurus, Alamosaurus,
Saltasaurus, etc. etc.)
-----unnamed group
------?Sereno et al.s new Saharan sauropod?
-------unnamed group
---------Euhelopidae (incl. Euhelops, Mamenchisaurus, Omeisaurus, etc.)
---------unnamed group
----------another unnamed group
-----------Diplodocidae (incl. Diplodocus, Apatosaurus, Barosaurus,
Tornieria, etc.)
-----------Dicraeosauridae (incl. Dicraeosaurus, Amaragasaurus, etc.)

Ornithischia will be presented in a later posting.  Bye for now.

Thomas R. Holtz, Jr.                                   
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092