Sauropod Necks How much do we really know
- Slides: 80
Sauropod Necks How much do we really know? Mike Taylor University of Bristol dino@miketaylor. org. uk Matt Wedel Western University mathew. wedel@gmail. com Almost nothing, it turns out.
Why sauropod necks matter Sander and Clauss 2008: fig. 1
The Berlin Brachiosaur
The Carnegie Diplodocus
The Carnegie Apatosaurus
Mamenchisaurus
Sauropod neck skeletons are misleading for three reasons. 1. Incompleteness
The Berlin Brachiosaur Giraffatitan brancai MB. R. 2181 (HMN SII) Janensch 1950 b Plate VIII
The Berlin Brachiosaur Giraffatitan brancai MB. R. 2181 (HMN SII) Janensch 1950 b Plate VIII
The Carnegie Diplodocus CM 84 & 82 Hatcher 1901 Composite from Plate III
The Carnegie Diplodocus CM 84 & 82 Hatcher 1901 Composite from Plate III
The Carnegie Diplodocus CM 84 & 82 Hatcher 1901 Composite from Plate III
Hatcher 1901 Plate I
The Carnegie Apatosaurus CM 3018 Gilmore 1936 Plate XXIV
The Carnegie Apatosaurus CM 3018 Gilmore 1936 Plate XXIV
Why incompleteness?
Taphonomy of Sauroposeidon Wedel et al. 2000
Gilmore 1925, plate X Baby Camarasaurus
Sauropod neck skeletons are misleading for three reasons. 1. Incompleteness 2. Distortion
The Rutland Cetiosaurus
The Rutland Cetiosaurus
The Carnegie Diplodocus CM 84 & 82 Hatcher 1901 Composite from Plate III
Cervicals 2 and 3 of Giraffatitan HMN SI
Why distortion? Wedel 2005
Wedel 2005
Sauropod neck skeletons are misleading for three reasons. 1. Incompleteness 2. Distortion 3. Absent cartilage
51 cm 41 cm +25%
+25%
Not likely as much as 25% because a baby giraffe is: A. a baby (though SII is also subadult) B. not a dinosaur How much cartilage does a domestic turkey have in its neck?
255 mm turkey neck Articulated vertebrae are 226 mm long => must add 12% to bone-only length
Domestic turkey
Domestic turkey Anterior articulation
Domestic turkey in ONP 16º
Domestic turkey Synovial joint extends centrum length by 12%
Domestic turkey in true neutral pose 44º
Domestic turkey neutral poses 28º difference
760 mm adult ostrich neck Articulated vertebrae are 701 mm long => must add 8% to bone-only length (Matt Cobbley, pers. Comm. )
Were sauropod necks more like Those of giraffes or birds? Birds are more closely related. BUT gross vertebral morphology is more like that of giraffes, e. g. opisthocoelous articulations.
Domestic turkey, C 8, posteroventral view 12 mm long when fresh
Domestic turkey, C 8, posteroventral view 10 mm long after simmering
Domestic turkey, C 8, posteroventral view 9. 5 mm long after scraping off cartilage
Domestic turkey, C 8, posteroventral view A 9. 5 mm zygapophysis gains 26% in length with cartilage
Domestic turkey, C 8, posteroventral view 26% A 9. 5 mm zygapophysis gains in length with cartilage
Dude, where's my cartilage?
* * * Complete, live neck Lose soft tissue Lose intervertebral cartilage Lose zygapophyseal cartilage Lose some of the bones Crush the remaining bones
* * * Complete, live neck Lose soft tissue Lose intervertebral cartilage Lose zygappophyseal cartilage Lose some of the bones Crush the remaining bones Then try to digitally manipulate the results!
Bones do not tell us everything! JOURNAL OF MORPHOLOGY 123: 456 -789 (2011) Osteology of the trunk of the African Elephant (Loxodonta africana) Simeon Halibutwrangler Institut für Biologie, Universität Scheinken, Schinkenstraße, Schinkenschloss, Germany. ABSTRACT Uh … Hey, wait! Look at that rabbit!
Sauropod neck skeletons are misleading for three reasons. 1. Incompleteness 2. Distortion 3. Absent cartilage
Sauropod neck skeletons are misleading for three reasons. 1. Incompleteness 2. Distortion 3. Absent cartilage So what should we do?
Extant analogues? But what?
Extant analogues? But what? In isolation, yields untestable or misleading results.
Phylogenetic bracketing
Phylogenetic bracketing
1. Bird and dinosaur pneumaticity O'Connor and Claessens 2005
2. Tetrapod neck posture Taylor et al. 2009
3. More archosaur limb cartilage Bonnan 2010
3. Archosaur limb cartilage Holliday et al. 2010 Alligator elbow
3. Yet more archosaur limb cartilage Mallison 2010
3. Yet more archosaur limb cartilage Mallison 2010 Extinct analogues?
Phylogenetic bracketing often gives answers that are less precise but more accurate. And so, the punchline: We must be prepared to accept rigidly defined areas of doubt and uncertainty.
Acknowledgement Thanks to all the animals that gave their lives for dissection.