The imagery on this page is the basis for a paper entitled Dispersal and diversity in the earliest North American sauropodomorph dinosaurs, with a description of a new taxon, by T.B. Rowe, H.-D. Sues and R.R. Reisz (2010, Proceedings of the Royal Society B, Biological Sciences, FirstCite). The Summary is as follows:
Sauropodomorph dinosaurs originated in the Southern Hemisphere in the Middle or Late Triassic and are commonly portrayed as spreading rapidly to all corners of Pangaea as part of a uniform Late Triassic to Early Jurassic cosmopolitan dinosaur fauna. Under this model, dispersal allegedly inhibited dinosaurian diversification, while vicariance and local extinction enhanced it. However, apomorphy-based analyses of the known fossil record indicate that sauropodomorphs were absent in North America until the Early Jurassic, reframing the temporal context of their arrival. We describe a new taxon from the Kayenta Formation of Arizona that comprises the third diagnosable sauropodomorph from the Early Jurassic of North America. We analysed its relationships to test whether sauropodomorphs reached North America in a single sweepstakes event or in separate dispersals. Our finding of separate arrivals by all three taxa suggests dispersal as a chief factor in dinosaurian diversification during at least the early Mesozoic. It questions whether a ‘cosmopolitan’ dinosaur fauna ever existed, and corroborates that vicariance, extinction and dispersal did not operate uniformly in time or under uniform conditions during the Mesozoic. Their relative importance is best measured in narrow time slices and circumscribed geographical regions.
About the Species
This specimen was collected from the Lower Jurassic Kayenta Formation, Dilophosaurus Quarry, Navajo Nation. It was made available to The University of Texas High-Resolution X-ray CT Facility for scanning by Dr. Timothy Rowe of The University of Texas at Austin. Funding for scanning and image processing was provided in part by a National Science Foundation Assembling the Tree of Life grant (IIS-0531767) to Dr. Rowe.
About this Specimen
This specimen was scanned by Matthew Colbert on 4 April 2007 along the horizontal axis for a total of 425 slices. Each 1024x1024 pixel slice is 0.1668 mm thick, with an interslice spacing of 0.1668 mm and a field of reconstruction of 79 mm.
Archibald, J. D. et al. 2010 Multiple causes, not a single cause for the terminal
Cretaceous extinctions. Science 328, 973.
Attridge, J., Crompton, A. W. & Jenkins, F. A. Jr. 1985 The southern African
Liassic prosauropod Massospondylus discovered in North America. J. Vert.
Paleont. 5, 128-132.
Benton, M. J. 1987 Progress and competition in macroevolution. Biol. Rev. 62,
Brusatte, S. L., Benton, M. J., Ruta, M. & Lloyd, G. T. 2008 Superiority,
competition, and opportunism in the evolutionary radiation of dinosaurs. Science
321, 1485-1488. (doi: 10.1126/science.1161833)
Brusatte, S. L., Nesbitt, S. J., Irmis, R. B., Butler, R. J., Benton, M. J. & Norell,
M. A. 2010 The origin and early radiation of dinosaurs. Earth-Sci. Rev. 101,
Butler, R. J., Upchurch, P. & Norman, D. B. 2008 The phylogeny of
ornithischian dinosaurs. J. Syst. Palaeont. 6, 1-40.
Colbert, E. H. 1973 Wandering lands and animals. New York, NY: Dutton.
Colbert, E. H. 1981 A primitive ornithischian dinosaur from the Kayenta
Formation of Arizona. Mus. N. Arizona Bull. 83, 1-61.
Crompton, A. W. & Attridge, J. 1986 Masticatory apparatus of the larger
herbivores during Late Triassic and Early Jurassic times. In The beginning of the
Age of Dinosaurs: faunal change across the Triassic- Jurassic boundary (ed K.
Padian), pp. 223-236. New York, NY: Cambridge University Press.
Donoghue, M. J., Doyle, J., Gauthier, J. A., Kluge, A. G. & Rowe, T. 1989 Importance
of fossils in phylogeny reconstruction. Ann. Rev. Ecol. Syst. 20, 431-460.
Fedak, T. 2006 A rich bone bed of sauropodomorph dinosaurs in the Early
Jurassic (Hettangian) McCoy Brook Formation. J. Vert. Paleont. 26 (Suppl. to 3),
Galton, P. M. & Upchurch, P. 2004 Prosauropoda. In The Dinosauria (eds. D.
B. Weishampel, P. Dodson, and H. Osmólska), pp. 232-258, 2nd edn. Berkeley,
CA: University of California Press.
Gauthier, J. A., Kluge, A. G. & Rowe, T. 1988 Amniote phylogeny and the
importance of fossils. Cladistics 4, 105-209.
Golonka, J. 2007 Late Triassic and Early Jurassic palaeogeography of the world.
Palaeogeogr. Palaeoclim. Palaeoecol. 244, 297-307.
Gow, C. E., Kitching, J. W. & Raath, M. A. 1990 Skulls of the prosauropod
dinosaur Massospondylus carinatus Owen in the collections of the Bernard Price
Institute for Palaeontological Research. Palaeont. Afr. 27, 45-58.
Grande, L. 1985 The use of palaeontology in systematics and biogeography, and
a time control refinement for historical biogeography. Paleobiology 11, 234-243.
Holtz, T. R., Chapman, R. E. & Lamanna, M. C. 2004 Mesozoic biogeography
of Dinosauria. In The Dinosauria (eds D. B. Weishampel, P. Dodson & H.
Osmólska), pp. 627-642, 2nd edn. Berkeley, CA: University of California Press.
Hunn, C. A. & Upchurch, P. 2001 The importance of time/space in diagnosing
the causality of phylogenetic events: towards a ‘chronobiogeographical’
paradigm? Syst. Biol. 50, 391–407.
Irmis, R. B., Parker, W. G. & Nesbitt, S. J. 2007 Early ornithischian dinosaurs:
the Triassic record. Hist. Biol. 19, 3-22.
Kent, D. V. & Olsen, P. E. 2008 Early Jurassic magnetostratigraphy and
paleolatitudes from the Hartford continental rift basin (eastern North America):
testing for polarity bias and abrupt polar wander in association with the Central
Atlantic Magmatic Province. J. Geophys. Res. 113, 6101-6124.
Langer, M. C., Ezcurra, M. D., Bittencourt, J. S. & Novas, F. E. 2010 The origin
and early evolution of dinosaurs. Biol. Rev. 85, 55-110.
Maddison, D. & Maddison, W. 2000 MacClade 4: analysis of phylogeny and
character evolution. Sunderland, MA: Sinauer Associates.
Martínez, R. N. 2009 Adeopapposaurus mognai, gen et sp. nov. (Dinosauria:
Sauropodomorpha), with comments on adaptations of basal Sauropodomorpha.
J. Vert. Paleont. 29, 142-164.
Marzoli, A., Renne, P. R., Piccirillo, E. M., Ernesto, M., Bellieni, G. & De Min,
A. 1999 Extensive 200-million- year-old continental flood basalts of the Central
Atlantic Magmatic Province. Science 284, 616-618.
Nesbitt, S. J., Irmis, R. B. & Parker, W. G. 2007 A critical re-evaluation of the
Late Triassic dinosaur taxa of North America. J. Syst. Palaeont. 5, 209-243.
Nesbitt, S. J., Smith, N. D., Irmis, R. B., Turner, A. H., Downs, A. & Norell, M.
A. 2009 A complete skeleton of a Late Triassic saurischian and the early
evolution of dinosaurs. Science 326, 1530-1533.
Padian, K. 1989 The presence of the dinosaur Scelidosaurus indicates Jurassic age
for the Kayenta Formation (Glen Canyon Group, northern Arizona). Geology 17,
Parker, W. G., Irmis, R. B., Nesbitt, S. J., Martz, J. W. & Browne, L. S. 2005
The Late Triassic pseudosuchian Revueltosaurus callenderi and its implications
for the diversity of early ornithischian dinosaurs. Proc. R. Soc. Lond. B 272, 963- 969.
Sander, P. M., Christian, A., Clauss, M., Fechner, R., Gee, C. T., Griebeler,
E.-M., Gunga, H.-C., Hummel, J., Mallison, H., Perry, S. F., Preuschoft, H.,
Rauhut, O. W. M., Remes, K., Tütken, T., Wings, O. & Witzel, U. 2010 Biology
of the sauropod dinosaurs: the evolution of gigantism. Biol. Rev.
Schaltegger, U., Geux, J., Bartolini, A., Schoene, B. & Ovtcharova, M. 2008
Precise U-Pb constraints for end-Triassic mass extinction, its correlations to
volcanism and Hettangian post-extinction recovery. Earth Planet. Sci. Let. 267,
Scotese, C. R. 2010. PALEOMAP Project. Arlington, Tx, University of Texas at Arlington, www.scotese.com.
Sereno, P. C. 1997 The origin and evolution of dinosaurs. Ann. Rev. Earth
Planet. Sci. 25, 435-489.
Sereno, P. C. 1999 The evolution of dinosaurs. Science 284, 2137-2147.
Sereno, P. C. 2007 Basal Sauropodomorpha: historical and recent phylogenetic
hypotheses, with comments on Ammosaurus major (Marsh, 1889). In Evolution
and palaeobiology of early sauropodomorph dinosaurs (eds P. M. Barrett & D. J.
Batten), pp. 261-289. Special Papers in Palaeontology 77.
Sertich, J. J. W. & Loewen, M. A. 2010 A new basal sauropodomorph dinosaur
from the Lower Jurassic Navajo Sandstone of southern Utah. PLoS One 5, e9789.
Smith, N. D. & Pol, D. 2007 Anatomy of a basal sauropodomorph dinosaur from
the Early Jurassic Hanson Formation of Antarctica. Acta Palaeont. Pol. 52,
Sues, H.-D. 1986 The skull and dentition of two tritylodontid synapsids from the
Lower Jurassic of western North America. Bull. Mus. Comp. Zool. (Harvard
Univ.) 151, 217-268.
Sues, H.-D., Clark, J. M. & Jenkins, F. A. Jr. 1994 A review of the Early
Jurassic tetrapods from the Glen Canyon Group of the American Southwest. In In
the shadow of the dinosaurs (eds N. C. Fraser & H.-D. Sues), pp. 284-294. New
York, NY: Cambridge University Press.
Swofford, D. 2002 Phylogenetic analysis using parsimony (and other methods)
4.0 beta for Macintosh. Sunderland, MA: Sinauer Associates.
Turner, A. H. 2004 Crocodyliform biogeography during the Cretaceous: evidence
of Gondwanan vicariance from biogeographical analysis. Proc. R. Soc. Lond. B
271, 2003-2009. (doi: 10.1098/rspb.2004.2840)
Tykoski, R. S., Rowe, T., Ketcham, R. & Colbert, M. 2002 Calsoyasuchus
valliceps, a new crocodyliform from the Early Jurassic Kayenta Formation of
Arizona. J. Vert. Paleont. 22, 593-611.
Upchurch, P., Hunn, C. A. & Norman, D. B. 2002 An analysis of dinosaurian
biogeography: evidence for the existence of vicariance and dispersal patterns
caused by geological events. Proc. R. Soc. Lond. B 269, 613-621.
Upchurch, P., Barrett, P. M. & Galton, P. M. 2007 A phylogenetic analysis of
basal sauropodomorph relationships: implications for the origin of sauropod
dinosaurs. In Evolution and palaeobiology of early sauropodomorph dinosaurs
(eds P. M. Barrett & D. J. Batten), pp. 57-90. Special Papers in Palaeontology 77.
Wilkinson, M. 1995 Coping with abundant missing entries in phylogenetic
inference using parsimony. Syst. Biol. 44, 501–514.
Wilkinson, M. 2001 REDCON 3.0: software and documentation. London:
Department of Zoology, Natural History Museum.
Wilkinson, M. 2001 TAXEQ3. Software and documentation. London: Department
of Zoology, Natural History Museum.
Yates, A. M. 2004 Anchisaurus polyzelus (Hitchcock): The smallest known
sauropod dinosaur and the evolution of gigantism among sauropodomorph
dinosaurs. Postilla 230, 1-58.
Yates, A. M. 2007 The first complete skull of the Triassic dinosaur
Melanorosaurus Haughton (Sauropodomorpha: Anchisauria). In Evolution and
palaeobiology of early sauropodomorph dinosaurs (eds P. M. Barrett & D. J.
Batten), pp. 9-55. Special Papers in Palaeontology 77.
Yates, A. M. 2010 A revision of the problematic sauropodomorph dinosaurs from
Manchester, Connecticut and the status of Anchisaurus Marsh. Palaeontology 53,
Front page image.