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Re: Spinosaurus proportions/limbsize/exploding head quotient



Heinrich Mallison <Heinrich.Mallison@mfn-berlin.de> wrote:


> There is, as THE man for skeletal drawings points out, something fishy about 
> the reconstruction: the pelvis and hind limbs are too small.
> By quite a bit - at least if you prefer to believe in the published bone 
> measurements rather than in the reconstruction fiugre


Yes, one can accept that _Spinosaurus_ was a semi-aquatic predator
without necessarily subscribing to the super-undersized pelvis and
hindlimbs.  Further, quadrupedal terrestrial locomotion implies weight
support and stride generation, neither of which squares with the
pectoral/forelimb morphology.

The hindlimbs of _Spinosaurus_ are interesting for other reasons,
including pachyostosis (solid long bones) and the pedal morphology
(especially the longer pedal digit I).  The latter would have put the
first toe in contact with the substrate - again consistent with a
semi-aquatic lifestyle, since it would likely have improved the foot's
purchase on soft ground (as the authors suggest).  However, I'd be
reluctant to put too much stock in this feature (longer pedal digit
I), because the condition in other spinosaurids is not known, and it
might simply reflect loss of cursorial ability rather than being a
semi-aquatic adaptation per se (cf. _Patagopteryx_).




Cheers
Tim

> http://www.skeletaldrawing.com/home/theres-something-fishy-about-spinosaurus9112014
>
> Why am I not surprised? Because the published figure is just too ridiculous.
> Personally, I also have doubts about the identification of the caudal 
> positions. The moment you shift them further back you can add anterior 
> caudals with bigger spines, which may mean more mass in the tail base, which 
> again shifts the center of mass backward.
>
> Spinosaurus - not quite as weird as Figure S3 of Ibrahim et al. 2014 makes 
> you believe.
>
>
> Dr. Heinrich Mallison
> Museum für Naturkunde - Leibniz Institute
> for Evolution and Biodiversity Science
> Invalidenstrasse 43
> 10115 Berlin
> Germany
> office: +49 (0)30 2093 8975
> cell: +49 (0)179 5429922
> email: heinrich.mallison@gmail.com, heinrich.mallison@mfn-berlin.de
> blog: dinosaurpalaeo.wordpress.com
>
> ________________________________________
> From: owner-DINOSAUR@usc.edu [owner-DINOSAUR@usc.edu] on behalf of Thomas R. 
> Holtz, Jr. [tholtz@umd.edu]
> Sent: Friday, September 12, 2014 1:33 PM
> To: bucketfoot-al@justice.com; DINOSAUR@usc.edu
> Subject: RE: Spinosaurus proportions/limbsize/exploding head quotient
>
> Some notes:
>
> 17 m goes way beyond what they extrapolate. They suggest that the larger 
> known specimens indicate a 15 m length.
>
> We have zero evidence of sexual dimorphism in sail size, so any conclusions 
> based on variations of these are mere speculation. Could be correct, could be 
> totally wrong. Need fossils to say something more definite. For that matter, 
> there is zero evidence of gregariousness in spinosaurids, so we can't assume 
> group-related behaviors in taxa we don't know lived in groups.
>
> The legs do belong to the new vertebral material, so those proportions are 
> correct. The arms? That is a different story. If you read the Supporting 
> Online Materia
> nd separately, from different individuals, and not in articulation 
> (obviously). So we don't know if the within-arm proportions are correct, or 
> if the arms were truly so huge on the individual shown.
>
> Sarcosuchus (the croc you mention) was discovered and named by French 
> paleontologists in the 1960s; Sereno's discovery was a new, more complete 
> specimen.
>
> Thomas R. Holtz, Jr.
> Email: tholtz@umd.edu   Phone: 301-405-4084
> Office: Centreville 1216
> Senior Lecturer, Vertebrate Paleontology
> Dept. of Geology, University of Maryland
> http://www.geol.umd.edu/~tholtz/
> Fax: 301-314-9661
>
> Faculty Director, Science & Global Change Program, College Park Scholars
> http://www.geol.umd.edu/sgc
> Fax: 301-314-9843
>
> Mailing Address:        Thomas R. Holtz, Jr.
>                         Department of Geology
>                         Building 237, Room 1117
>                         University of Maryland
>                         College Park, MD 20742 USA
>> -----Original Message-----
>> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] On Behalf Of 
>> Vlad Petnicki
>> Sent: Friday, September 12, 2014 6:17 AM
>> To: DINOSAUR@usc.edu
>> Subject: Spinosaurus proportions/limbsize/exploding head quotient
>>
>> Well, I imagine that the classic scene from the sci fi movie "Scanners" has 
>> been repeated several hundred, heck, million-fold today!
>>
>> Spinosaurus, one of the truly weird dinosaurs to begin with, turns out to be 
>> perhaps THE most bizarre dino discovered to date!
>>
>> Essentially it looks like a 17-meter long torpedo with arms, legs and that 
>> humongous sail.
>>
>> Before anyone else claims it, what do the pros out there think of my 
>> observation that one of the uses of that sail may have beento
>> help the animals identify the "Alpha Male" while they were all submerged in 
>> the water, in order to keep everybody in line?  (I guess
>> that falls into the "display" category vis-a-vis the purpose of the sail).
>>
>> What is more fascinating to me is the possibility that the sail also added 
>> extra ballast - indeed, its shorter-sailed relatives did not have
>> th
> work - the more aquatic, the bigger the sail?)
>>
>> Lots of folks are properly cautious about making sure this new skeletal 
>> reconstruction didn't make the mistake of pairing the legs of a
>> smaller animal with the body of a fully grown adult - I am assuming here 
>> that someone with Sereno's background would make
>> quadruple-sure that there was no evidence of a mass-burial at the excavation 
>> site.
>>
>> Sereno sure has carved his niche out, hasn't he?  Finder of Suchomimus, the 
>> giant croc whose name escapes me, and now
>> collaborating on "solving" the 100-year old mystery of Spinosaurus - this 
>> was really a joint effort, starting with Stromer and then
>> involving the Italians, Ibrahim, and Sereno.
>>
>> I hope its all backed up and airtight.
>>
>> Tom Holtz is right - this is a "nuclear bomb" going off in the middle of the 
>> dino-phile community!!!!
>>
>> Awesome stuff!!
>>
>> --- DINOSAUR@usc.edu wrote:
>>
>> From: DINOSAUR@usc.edu
>> To: Dinosaur Discussion List  <DINOSAUR@usc.edu>
>> Subject: DINOSAUR digest 1677
>> Date: Fri, 12 Sep 2014 00:04:08 PDT
>>
>>
>>                           DINOSAUR Digest 1677
>>
>> Topics covered in this issue include:
>>
>>   1) Ikrandraco, new crested pterosaur from Early Cretaceous of China  (free 
>> pdf)
>>       by Ben Creisler <bcreisler@gmail.com>
>>   2) Dinosaur tracksites from Lower Jurassic of Languedoc-Roussillon, France.
>>       by Ben Creisler <bcreisler@gmail.com>
>>   3) Re: Dinosaur tracksites from Lower Jurassic of Languedoc-Roussillon, 
>> France.
>>       by Ben Creisler <bcreisler@gmail.com>
>>   4) Spinosaurus countdown begins...
>>       by Ben Creisler <bcreisler@gmail.com>
>>   5) RE: Spinosaurus countdown begins...
>>       by "Thomas R. Holtz, Jr." <tholtz@umd.edu>
>>   6) Re: Spinosaurus countdown begins...
>>       by Ben Creisler <bcreisler@gmail.com>
>>   7) RE: Spinosaurus countdown begins...
>>       by "Thomas R. Holtz, Jr." <tholtz@umd.edu>
>>   8) Spinosaurus redescribed as giant semiaquatic theropod
>>       by Ben Creisler <bcreisler@gmail.com>
>>   9) Re: Spinosaurus redescribed as giant semi
>>       by Ben Creisler <bcreisler@gmail.com>
>>  10) Re: Spinosaurus countdown begins...
>>       by Luis Rey <luisrey@ndirect.co.uk>
>>  11) Re: Spinosaurus redescribed as giant semiaquatic theropod
>>       by Dann Pigdon <dannj@alphalink.com.au>
>>  12) Re: Spinosaurus redescribed as giant semiaquatic theropod
>>       by Ben Creisler <bcreisler@gmail.com>
>>
>>
>>
>>
>> _____________________________________________________________
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