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Time Line - dinosaur originations

Below is a list of stage-by-stage appearances of major dinosaur groups
(mostly families).  A seperate message (probably next week) will include
dinosaur extinctions.

Maastrichtian           no change at familial level

Campanian               First Ornithomimidae, Tyrannosauridae, Elmisauridae, 
                Avimimidae, Oviraptoridae, Noasauridae (Theropoda), 
                Pachycephalosauridae, Homalocephalidae
                        Centrosaurinae, Chasmosaurinae (Ceratopsidae)

Santonian               nothing new known (many previously-thought Santonian 
                now considered early    Campanian)

Coniacian               Advanced coelurosaur-like abelisauroids (Alvarezsaurus, 

Turonian                First Oviraptorosauria (Theropoda), Hadrosauridae 
                (Ornithopoda), Protoceratopsidae, Ceratopsidae

Cenomanian              nothing new known

Albian                  nothing new known

Aptian                  First Abelisauridae,Troodontidae, Therizinosauroidea 
                (Theropoda), Ankylosauridae (Ankylosauria),
                (first Ceratopsia: Marginocephalia)

Barremian               First Dromaeosauridae, Spinosauridae (Theropoda),       
                ?Pachycephalosauria (Marginocephalia)

Hauterivian             nothing new known

Valanginian             nothing new known

Berriasian              First Ornithomimosauria (Theropoda), Iguanodontidae 
                (Ornithopoda), Stenopelix (first Marginocephalia)

Tithonian               nothing new known

Kimmeridgian            First birds, best early Coelurosauria (Compsognathus
                Ornitholestes, Coelurus, etc.: Theropoda), Titanosauria 
                (Sauropoda),    Polacanthidae (Ankylosauria), Iguanodontia 
                (Camptosaurus, Dryosaurus: Ornithopoda)
Oxfordian               First Camarasauridae, Euhelopidae (Sauropoda)

Callovian       First Allosauridae (Theropoda), Nodosauridae (first
                        Hypsilophodontidae (Ornithopoda)

Bathonian               First Brachiosauridae (Sauropoda), Stegosauridae

Bajocian                First Cetiosauridae, Diplodocidae (Sauropoda)   

Aalenian                First Megalosauridae (Theropoda)

Toarcian                nothing new known

Pliesbachian            First Anchisauridae (Prosauropoda), Stegosauria

Sinemurian              First Ceratosauridae? (Sarcosaurus: Theropoda), First
                Thyreophora (Scuttelosaurus, Scelidosauridae), 

Hettangian              First Dilophosaurus (Theropoda) Massospondylidae, 
                Yunnanosauridae (Prosauropoda), Vulcanodontidae
                Heterodontosauridae (Ornithopoda)

Rhaetian                nothing new known

Norian                  First Plateosauridae, Melanorosauridae (both 

Carnian                 First true dinosaurs: Theropoda (Eoraptor,
                Coelophysoidea),        Prosauropoda (Thecodontosauridae),
                Ornithischia (Pisanosaurus)

Ladinian                First dinosauromorphs (Lagerpeton, Marasuchus, etc.)
Thomas R. Holtz, Jr.                            tholtz@geochange.er.usgs.gov
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