2003 Seattle Annual Meeting (November 2–5, 2003)

Paper No. 16
Presentation Time: 5:15 PM

GENERIC RICHNESS OF NON-AVIALAN DINOSAURIA


FASTOVSKY, David E.1, HUANG, Yifan2, HSU, Jason C.2, WEISHAMPEL, David B.3, MARTIN-MACNAUGHTON, Jamie4 and SHEEHAN, Peter5, (1)Department of Geosciences, Univ of Rhode Island, 9 East Alumni Ave, Kingston, RI 02881, (2)Department of Statistics, The Ohio State Univ, Columbus, OH 43210, (3)Cell Biology & Anatomy, The Johns Hopkins Univ School of Medicine, 725 N. Wolfe St, Baltimore, MD 21205, (4)Department of Geological Sciences, Brown Univ, Providence, RI 02912, (5)Milwakee Public Museum, Milwaukee, WI, defastov@uri.edu

We have revisited the question of Mesozoic non-avialian dinosaur richness using a new global compilation of dinosaur genera from the second edition of The Dinosauria (in press).  Considering body fossils only, this consists of 556 different genera distributed by stage among the Late Triassic (37), Early Jurassic (33), Middle Jurassic (38); Late Jurassic (64); Early Cretaceous (143); and Late Cretaceous (241).  At this level of resolution, dinosaur generic richness unambiguously and dramatically increases throughout their tenure on Earth.  Within the Late Cretaceous, the number of different dinosaur genera increases, reaching a peak in the Campanian (59), but decreasing (39) in the Maastrichtian. 

Because the database is constructed on published records of dinosaur taxa, 39% of all genera have more than one entry.  This suggests an approach allowing comparison by rarefaction:  the published records are treated as repeats in a counting experiment.  Because rarefaction always adjusts downward to the smallest sample, we used Cenomanian (n=48) and rarified samples from the Turonian, Coniacian, Santonian, Campanian, and Maastrichtian. 

 

 

Cenomanian

Turonian

Coniacian

Santonian

Campanian

Maastrichtian

# counts

48

51

62

48

257

292

# genera found

37

43

50

38

106

81

Estimated richness

(37)

41

41

(38)

36

31

Standard deviation

(0)

1.4

2.6

(0)

3.9

3.6

 

When this is done the estimated diversity in the Maastrichtian becomes statistically indistinguishable from estimated diversity in the Campanian.  The counts show no obvious relationship to length of time, suggesting that some aspect of real diversity is reflected in these numbers.