Brachiosaurus brancai is not Brachiosaurus Michael P Taylor

Brachiosaurus brancai is not Brachiosaurus Michael P. Taylor Palaeobiology Research Group School of Earth and Environmental Sciences University of Portsmouth Burnaby Road, Portsmouth PO 1 3 QL ENGLAND dino@miketaylor. org. uk Brachiosaurus altithorax skeletal reconstruction (Taylor in press)

Brachiosaurus at O'Hare Airport, Chicago

Brachiosaurus at O'Hare Airport, Chicago But we we don't have the head Or Or the neck Or Or the scapula and anterior dorsals Or Or most of of the tail Or Or the lower forelimbs and forefeet Or Or the lower hindlimbs and hindfeet

Brachiosaurus brancai at the Humboldt Museum

Brachiosaurus brancai at the Humboldt Museum Most of what we think we know about Brachiosaurus, we really know about Brachiosaurus brancai.

Brachiosaurus brancai at the Humboldt Museum Most of what we think we know about Brachiosaurus, we really know about Brachiosaurus brancai. But is it Brachiosaurus?

Brachiosaurus altithorax Riggs 1903 Elements from Riggs (1904)

Brachiosaurus brancai Janensch 1914 Elements from Janensch (1922, 1929, 1935 -1936, 1950, 1961)

Migeod's Tendaguru brachiosaur (at the BMNH) Migeod (1931: fig. 1)

The Potter Creek humerus (found 1943) Jensen (1987: fig 3 E) Photographs by M. Brett-Surman

Subsequent Potter Creek material (1971 -1975) Jensen (1987: fig 3 E)

Dry Mesa (“Ultrasauros”) scapulocoracoid Curtice et al. (1996: fig. 1 A) Referred to B. altithorax by Paul (1988)

Felch Quarry skull Modified from Carpenter and Tidwell (1998: fig. 2) Carpenter and Tidwell (1998: fig. 1)

Jensen/Jensen rib (Jensen 1987: fig. 6 B) Other bits and pieces BYU 12866 and 12867 OMNH 01138 (Bonnan and Wedel 2004: fig. 1)

d e r r e f e r x a e r h o t h f t i o t l E a. N s g u n r i NO u c a n i s v o i n h o c c a s r i B l a i r e t a m All we really have to go on is the holotype FMNH P 25107

B. brancai compared with Brachiosaurus holotype Janensch mostly noted general similarity: “[Brachiosaurus brancai] is so close to the genus Brachiosaurus, so far as a the present state of preparation allows a judgement, that there was no recognisable reason to hold [it] separate from Brachiosaurus. ” – Janensch (1914: 83) “The dorsal vertebrae of the African Brachiosaurus brancai correspond extensively to those of Brachiosaurus altithorax” – Janensch (1950: 72) “The humerus of the type species of the genus Brachiosaurus altithorax Riggs (1904) from the Morrison Formation, is in broad terms so similar in outline to Br. brancai that a detailed comparison is unnecessary. ” – Janensch (1961: 187)

Janensch's 13 putative synapomorphies

Janensch's 13 putative synapomorphies OK OK

Janensch's 13 putative synapomorphies s e i h p r o m o p a n y s r u o F OK OK

The subgenus Brachiosaurus (Giraffatitan) Erected by Paul (1988) for “Brachiosaurus” brancai Separation asserted but not demonstrated. “The caudals, scapula, coracoid, humerus, ilium and femur of B. altithorax and B. brancai are very similar. . . it is in the dorsal column and trunk that the significant differences occur. ” Comparisons based in part on the dorsal BYU 9044 And on the scapulocoracoid BYU 9462

The subgenus Brachiosaurus (Giraffatitan) Erected by Paul (1988) for “Brachiosaurus” brancai Separation asserted but not demonstrated. “The caudals, scapula, coracoid, humerus, ilium and femur of B. altithorax and B. brancai are very similar. . . it is in the dorsal column and trunk that the significant differences occur. ” Comparisons based in part on the dorsal BYU 9044. . . which belongs to the diplodocid Supersaurus. And on the scapulocoracoid BYU 9462

The subgenus Brachiosaurus (Giraffatitan) Erected by Paul (1988) for “Brachiosaurus” brancai Separation asserted but not demonstrated. “The caudals, scapula, coracoid, humerus, ilium and femur of B. altithorax and B. brancai are very similar. . . it is in the dorsal column and trunk that the significant differences occur. ” Comparisons based in part on the dorsal BYU 9044. . . which belongs to the diplodocid Supersaurus. And on the scapulocoracoid BYU 9462. . . which is (bad) circular reasoning

Element-by-element comparisons Mostly based on personal examination. But Riggs's and Janensch's images are better than my photographs.

Anterior dorsal vertebrae

Posterior dorsal vertebrae

Dorsal ribs

Dorsal ribs Variation: serial and individual and asymmetrical

Sacrum

Sacrum ?

2 nd caudal vertebra

(Aside: does B. brancai have pneumatic caudals? )

Coracoid

Humerus

Humerus GI = 7. 53 (ratio of length to width) GI = 8. 69 (range 7. 86– 9. 19)

Humerus Probably just damage GI = 7. 53 (ratio of length to width) GI = 8. 69 (range 7. 86– 9. 19)

Ilium

Femur

Summary All informative elements differ between species: Dorsal vertebrae: 10 differences nd 2 Caudal vertebra: 7 differences Coracoid: 4 differences Humerus: 3 differences Ilium: 4 differences Femur: 3 differences Brachiosaurus altithorax and Brachiosaurus brancai differ more than Diplodocus and Barosaurus.

Systematic palaeontology DINOSAURIA Owen, 1842 SAURISCHIA Seeley, 1888 SAUROPODA Marsh, 1878 NEOSAUROPODA Bonaparte, 1986 MACRONARIA Wilson and Sereno, 1998 TITANOSAURIFORMES Salgado, Coria and Calvo, 1997 BRACHIOSAURIDAE Riggs, 1904 BRACHIOSAURUS Riggs, 1903 BRACHIOSAURUS ALTITHORAX Riggs, 1903 Holotype--FMNH P 25107 GIRAFFATITAN Paul, 1988 GIRAFFATITAN BRANCAI (Janensch, 1914) Lectotype--HMN SII

Systematic palaeontology DINOSAURIA Owen, 1842 SAURISCHIA Seeley, 1888 SAUROPODA Marsh, 1878 NEOSAUROPODA Bonaparte, 1986 MACRONARIA Wilson and Sereno, 1998 TITANOSAURIFORMES Salgado, Coria and Calvo, 1997 BRACHIOSAURIDAE Riggs, 1904 BRACHIOSAURUS Riggs, 1903 BRACHIOSAURUS ALTITHORAX Riggs, 1903 Holotype--FMNH P 25107 GIRAFFATITAN Paul, 1988 GIRAFFATITAN BRANCAI (Janensch, 1914) Lectotype--HMN SII Sorry!

Phylogenetic analysis Are Brachiosaurus and Giraffatitan closely related? I re-scored the matrix of Harris (2006) with separate Brachiosaurus and Giraffatitan OTUs. (By the way, 13 of the compound Brachiosaurus OTU's 331 characters were mis-scored -- 4%. )

Phylogenetic analysis Brachiosauridae remains monophyletic

Phylogenetic analysis Brachiosauridae remains monophyletic, but: Only one more step needed to split them up

Phylogenetic analysis Brachiosauridae remains monophyletic, but: Only one more step needed to split them up What would happen if we added other “brachiosaurs”?

Differences in body proportions The trunk is about 23% longer in Brachiosaurus Tail is deeper and probably longer Humeri may have been laterally deflected More robust humeri => may have carried a larger proportion of mass

Giraffatitan reconstruction (Paul 1988)

Brachiosaurus reconstruction (Taylor in press)

Acknowledgements I thank. . . Bill Simpson, David Unwin, Wolf-Dieter Heinrich and Sandra Chapman for access to specimens. Phil Mannion for photographs Gerhard Maier for translations of Janensch. Jerry Harris and Matt Wedel for reviews And I really am sorry about the name “Giraffatitan”.