How much do we really know?
80
How much do we really know? Sauropod Necks Mike Taylor University of Bristol [email protected] Matt Wedel Western University [email protected] Almost nothing, it turns out.
description
Sauropod Necks. How much do we really know?. Almost nothing, it turns out. Mike Taylor University of Bristol [email protected] Matt Wedel Western University [email protected]. Why sauropod necks matter. Sander and Clauss 2008:fig. 1. The Berlin Brachiosaur. - PowerPoint PPT Presentation
Transcript of How much do we really know?
How much do wereally know?
Sauropod Necks
Mike TaylorUniversity of [email protected]
Matt WedelWestern [email protected]
Almost nothing, it turns out.
Why sauropod necks matter
Sander and Clauss 2008:fig. 1
The Berlin BrachiosaurThe Berlin Brachiosaur
The Carnegie The Carnegie DiplodocusDiplodocus
The Carnegie The Carnegie ApatosaurusApatosaurus
MamenchisaurusMamenchisaurus
Sauropod neck skeletons are misleading for three reasons.
1. Incompleteness
The Berlin Brachiosaur
Giraffatitan brancaiMB.R.2181
(HMN SII)
Janensch 1950bPlate VIII
The Berlin Brachiosaur
Giraffatitan brancaiMB.R.2181
(HMN SII)
Janensch 1950bPlate VIII
The Carnegie DiplodocusCM 84 & 82
Hatcher 1901Composite from
Plate III
The Carnegie DiplodocusCM 84 & 82
Hatcher 1901Composite from
Plate III
The Carnegie DiplodocusCM 84 & 82
Hatcher 1901Composite from
Plate III
Hatcher 1901Plate I
The Carnegie ApatosaurusCM 3018
Gilmore 1936Plate XXIV
The Carnegie ApatosaurusCM 3018
Gilmore 1936Plate XXIV
Why incompleteness?Why incompleteness?
Wedel et al. 2000
Taphonomy of Sauroposeidon
Gilmore 1925, plate XBaby Camarasaurus
Sauropod neck skeletons aremisleading for three reasons.
1. Incompleteness
2. Distortion
The Rutland Cetiosaurus
The Rutland Cetiosaurus
The Carnegie DiplodocusCM 84 & 82
Hatcher 1901Composite from
Plate III
Cervicals 2 and 3 of Cervicals 2 and 3 of GiraffatitanGiraffatitan HMN SI HMN SI
Wedel 2005
Why distortion?
Wedel 2005
Sauropod neck skeletons aremisleading for three reasons.
1. Incompleteness
2. Distortion
3. Absent cartilage
51cm41cm+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 neckArticulated vertebrae are 226 mm long=> must add 12% to bone-only length
Domestic turkey
Domestic turkey
Anterior articulation
Domestic turkeyin ONP
16º
Domestic turkey
Synovial joint extendscentrum length by 12%
Domestic turkeyin true neutral pose
44º
Domestic turkeyneutral poses
28º difference
760 mm adult ostrich neckArticulated vertebrae are 701 mm long => must add 8% to bone-only length
(Matt Cobbley, pers. Comm.)
Were sauropod necks more likeThose of giraffes or birds?
Birds are more closely related.
BUT gross vertebral morphology ismore like that of giraffes, e.g.opisthocoelous articulations.
?
??
Domestic turkey, C8, posteroventral viewDomestic turkey, C8, posteroventral view
12 mm long12 mm longwhen freshwhen fresh
Domestic turkey, C8, posteroventral viewDomestic turkey, C8, posteroventral view
10 mm long10 mm longafter simmeringafter simmering
Domestic turkey, C8, posteroventral viewDomestic turkey, C8, posteroventral view
9.5 mm long9.5 mm longafter scrapingafter scrapingoff cartilageoff cartilage
Domestic turkey, C8, posteroventral viewDomestic turkey, C8, posteroventral view
A 9.5 mm zygapophysis gains 26%A 9.5 mm zygapophysis gains 26%in length with cartilagein length with cartilage
Domestic turkey, C8, posteroventral viewDomestic turkey, C8, posteroventral view
A 9.5 mm zygapophysis gains A 9.5 mm zygapophysis gains 26%26%in length with cartilagein length with cartilage
Dude, where's my cartilage?Dude, where's my cartilage?
* Complete, live neck* Complete, live neck* Lose soft tissue* Lose soft tissue* Lose intervertebral cartilage* Lose intervertebral cartilage* Lose zygapophyseal cartilage* Lose zygapophyseal cartilage* Lose some of the bones* Lose some of the bones* Crush the remaining bones* Crush the remaining bones
* Complete, live neck* Complete, live neck* Lose soft tissue* Lose soft tissue* Lose intervertebral cartilage* Lose intervertebral cartilage* Lose zygappophyseal cartilage* Lose zygappophyseal cartilage* Lose some of the bones* Lose some of the bones* Crush the remaining bones* Crush the remaining bones
Then try to digitally manipulate the results!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 aremisleading for three reasons.
1. Incompleteness
2. Distortion
3. Absent cartilage
Sauropod neck skeletons aremisleading for three reasons.
1. Incompleteness
2. Distortion
3. Absent cartilage
So what should we do?
Extant analogues? But what?Extant analogues? But what?
Extant analogues? But what?Extant analogues? But what?
In isolation, yields untestable orIn isolation, yields untestable ormisleading results.misleading results.
Phylogenetic bracketing
Phylogenetic bracketing
1. Bird and dinosaur pneumaticityO'Connor and Claessens 2005
2. Tetrapod neckpostureTaylor et al. 2009
3. More archosaur limb cartilageBonnan 2010
3. Archosaur limb cartilageHolliday et al. 2010
Alligator elbow
3. Yet more archosaur limb cartilageMallison 2010
3. Yet more archosaur limb cartilageMallison 2010
Extinct analogues?
Phylogenetic bracketing often gives answersthat are less precise but more accurate.
And so, the punchline:We must be prepared to accept rigidly
defined areas of doubt and uncertainty.
AcknowledgementAcknowledgement
Thanks to all the animalsThanks to all the animalsthat gave their lives forthat gave their lives fordissection.dissection.
