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Aquatic Adaptation of Spinosaurus


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Although the paper is paywalled the abstract provides some interesting insights 

 

The hypothesized aquatic habits of Spinosaurus have been called into question, and the distribution of aquatic habits within Spinosauridae remain unclear.  New spinosaurid specimens from the Kem Kem beds of Morocco reveal aquatic adaptations in the cranium.

 

1) Elevated orbits and bending of the frontals placed the eyes atop the skull, as in semiaquatic animals such as crocodiles and hippos.

2) Two morphologies are present, a smaller morph characterized by narrow, triangular frontals, and a larger morph characterized by broad, subrectangular frontals overlapping the prefrontals. The two morphs suggest two distinct spinosaurine taxa, and are tentatively referred to the spinosaurines Spinosaurus cf. aegyptiacus and Sigilmassasaurus brevicollis, respectively

 

Another interesting point in the abstract:

The appearance of giant semiaquatic dinosaurs may have followed the disappearance of giant pholidosaurid crocodylomorphs, suggesting that the extinction of large crocodylomorphs was associated with the rise of dinosaurs as apex predators in the freshwater ecosystem in North Africa.

 

https://www.sciencedirect.com/science/article/pii/S0195667117303427

Aquatic adaptation in the skull of carnivorous dinosaurs (Theropoda: Spinosauridae) and the evolution of aquatic habits in spinosaurus

Thomas M.S.Arden, Catherine G.Klein, SamirZouhri, Nicholas R.Longrich

 

From outline images frontals are shown.

Screenshot_20180719-113054.thumb.jpg.fcf271dec520d26c6463186e5a526553.jpg

 

@LordTrilobite

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LordTrilobite

That is indeed pretty interesting. Good to see further confirmation of two morphs of Spinosaurid. Also quite interesting that they consider these Spinosaurine and not one of them Baryonychine.

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2 hours ago, Troodon said:

The appearance of giant semiaquatic dinosaurs may have followed the disappearance of giant pholidosaurid crocodylomorphs, suggesting that the extinction of large crocodylomorphs was associated with the rise of dinosaurs as apex predators in the freshwater ecosystem in North Africa.

Maybe a case of Ectotherms losing out to  Endotherms? What do we know about the climate there, pre- and post-Spinosaurid?

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17 minutes ago, Auspex said:

Maybe a case of Ectotherms losing out to  Endotherms? What do we know about the climate there, pre- and post-Spinosaurid?

Definitely possible and don't know to your question but my hunch says there was not much of a change.  The paper might address that. Interesting thought

 

1 hour ago, LordTrilobite said:

That is indeed pretty interesting. Good to see further confirmation of two morphs of Spinosaurid. Also quite interesting that they consider these Spinosaurine and not one of them Baryonychine.

And they described one of the morphs as  "cf S. aegyptiacus"  another slap in the face to Ibrahim/Sereno 2014 paper

 

 

 

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  • 10 months later...

Two very prominent paleontologist recently published these comments

 

"In a recent paper, the contention that spinosaurine theropods were semi-aquatic was supported by Arden et al., (2018) and they provided a hypothetical sequence of acquisition of traits that had evolved in line with this lifestyle. However, we find that the presented traits were either loosely defined and / or are clearly distinct from those traits seen in extant animals with adaptations to life in water. Some spinosaurs may have spent extensive time in water, but the data to support this is currently insufficient and other hypotheses for their behaviour also fit the available data."

 

Paywalled

https://www.sciencedirect.com/science/article/pii/S0195667119300485

Comment on: Aquatic adaptation in the skull of carnivorous dinosaurs (Theropoda: Spinosauridae) and the evolution of aquatic habits in spinosaurids. 93: 275-284.

David Hone, Thomas Richard Holtz

https://doi.org/10.1016/j.cretres.2019.05.010

 

 

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Tidgy's Dad

If the Moroccan spinosaurids were not aquatic, semi-aquatic, amphibious or whatever, then they seemed to have spent an inordinate amount of time falling in the water, drowning, being fossilized and leaving their teeth in ponds. ;)

Perhaps their version of the tooth fairy was a mermaid. :default_rofl:

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On 6/13/2019 at 4:30 AM, Tidgy's Dad said:

If the Moroccan spinosaurids were not aquatic, semi-aquatic, amphibious or whatever, then they seemed to have spent an inordinate amount of time falling in the water, drowning, being fossilized and leaving their teeth in ponds. ;)

Perhaps their version of the tooth fairy was a mermaid. :default_rofl:

I respect Tom Holtz and David Hone opinions and since science deals in facts they have yet to be convinced with the evidence presented.    Guess its more homework for the orginal authors

 

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