Brachiosaurus brancai is not Brachiosaurus Michael P. Taylor Palaeobiology Research Group School of...

Brachiosaurus brancaiis not BrachiosaurusMichael P. Taylor

Palaeobiology Research GroupSchool of Earth and Environmental SciencesUniversity of PortsmouthBurnaby Road, Portsmouth PO1 [email protected]

Brachiosaurus altithoraxskeletal reconstruction(Taylor in press)

mailto:[email protected]

Brachiosaurus at O'Hare Airport, ChicagoBrachiosaurus at O'Hare Airport, Chicago

Brachiosaurus at O'Hare Airport, ChicagoBrachiosaurus at O'Hare Airport, Chicago

But we don't have the headOr the neckOr the scapula and anterior dorsalsOr most of the tailOr the lower forelimbs and forefeetOr the lower hindlimbs and hindfeet

But we don't have the headOr the neckOr the scapula and anterior dorsalsOr most of the tailOr the lower forelimbs and forefeetOr the lower hindlimbs and hindfeet

Brachiosaurus brancaiat the Humboldt MuseumBrachiosaurus brancaiat the Humboldt Museum


Most of what we thinkwe know aboutBrachiosaurus,

we really know aboutBrachiosaurus brancai.


Most of what we thinkwe know aboutBrachiosaurus,

we really know aboutBrachiosaurus 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 3E)

Photographs by M. Brett-Surman

Subsequent Potter Creek material (1971-1975)

Jensen (1987: fig 3E)

Dry Mesa (“Ultrasauros”) scapulocoracoid

Curtice et al.(1996: fig. 1A)

Referred toB. altithoraxby Paul (1988)

Felch Quarry skull

Modified fromCarpenter and Tidwell(1998: fig. 2)

Carpenter and Tidwell(1998: fig. 1)

Other bits and pieces

BYU 12866 and 12867

OMNH 01138 (Bonnanand Wedel 2004:fig. 1)

Jensen/Jensen rib(Jensen 1987: fig. 6B)

NONE of the referred

Brachiosaurus altithorax

material is convincing.NONE of the referred

Brachiosaurus altithorax

material is convincing.

All we really have to go on is the holotype FMNH P25107

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 fromBrachiosaurus.”

– Janensch (1914:83)

“The dorsal vertebrae of the African Brachiosaurus brancaicorrespond extensively to those of Brachiosaurus altithorax”

– Janensch (1950:72)

“The humerus of the type species of the genus Brachiosaurusaltithorax Riggs (1904) from the Morrison Formation, is in broadterms so similar in outline to Br. brancai that a detailedcomparison is unnecessary.”

– Janensch (1961:187)

Janensch's 13 putative synapomorphies


OKOK

OKOK


OKOK

OKOK

Four synapomorphies

Four synapomorphies

The subgenus Brachiosaurus (Giraffatitan)

Erected by Paul (1988) for “Brachiosaurus” brancai

Separation asserted but not demonstrated.

“The caudals, scapula, coracoid, humerus, ilium andfemur of B. altithorax and B. brancai are very similar ...it is in the dorsal column and trunk that the significantdifferences occur.”

Comparisons based in part on the dorsal BYU 9044

And on the scapulocoracoid BYU 9462





Comparisons based in part on the dorsal BYU 9044... which belongs to the diplodocid Supersaurus.

And on the scapulocoracoid BYU 9462





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 arebetter than my photographs.

Anterior dorsal vertebrae

Posterior dorsal vertebrae

Dorsal ribs

Dorsal ribs

Variation: serial and individual and asymmetricalVariation: serial and individual and asymmetrical

Sacrum

Sacrum

??

2nd 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

GI = 7.53(ratio of length to width) GI = 8.69 (range 7.86–9.19)

Probablyjust damage

Summary

All informative elements differ between species: Dorsal vertebrae: 10 differences 2nd Caudal vertebra: 7 differences Coracoid: 4 differences Humerus: 3 differences Ilium: 4 differences Femur: 3 differences

Brachiosaurus altithorax and Brachiosaurus brancaidiffer 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!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's331 characters were mis-scored -- 4%.)


Brachiosauridae remains monophyletic


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


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”.

Brachiosaurus brancai is not Brachiosaurus Michael P. Taylor Palaeobiology Research Group School of...

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