[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: [dinosaur] Spinosaurus tail propelled swimming locomotion

Large regions of northern Patagonia, northeastern Argentina, and Bolivia were covered by a shallow sea (prime locations to fine spinosaurids), and some restricted fore-arc marine basins were developed on the coast of central Chile. Marine sedimentation was also continuous throughout most of Late Cretaceous time in the Atlantic basins of southern Brazil and central Argentina. Continental deposition was restricted to central Patagonia and the intra-cratonic Paraná Basin. The transgressive-regressive pattern of the Andean Basin appears to have been controlled by regional tectonics in an area in which local vertical movements were greater than global sea-level changes. In the Austral Basin a different transgressive-regressive pattern emerged, as local tectonic movements could not completely overprint the record of global changes of sea level. Widespread marine sedimentation in a series of Atlantic and Pacific basins during late Late Cretaceous time was coincident with a worldwide transgressive peak.

 

Lower-Middle Cretaceous has produced spinosaurids ( Irritator challengeri and Angaturama limai from the Romualdo Formation, Araripe Basin, Brazil; Oxalaia quilombensis, Cenomanian northeast Brazil, Alcântara Formation, Itapecuru Group of the São Luís-Grajaú Basin: these sediments were deposited under marine and fluvial conditions similar to those of the Bahariya Formation in Egypt, where Spinosaurus remains have been found) but coastal or near shore vertebrate deposits are scarce, with invertebrates known mainly from west-central Argentina, whereas Upper Cretaceous invertebrates are known almost exclusively from southern Patagonia. Vertebrates are most common in continental Upper Cretaceous strata of central-northern Patagonia and southern Brazil (as you indicated below: unnamed Baryonychinae, Adamantina Formation, Bauru Group, Brazil).

 

References:

https://www.researchgate.net/publication/44515466_The_Cretaceous_System_of_Southern_South_America/link/55c0dcc808aec0e5f448892b/download

 

From: dinosaur-l-request@mymaillists.usc.edu <dinosaur-l-request@mymaillists.usc.edu> On Behalf Of Mickey Mortimer
Sent: Saturday, May 2, 2020 1:47 AM
To: dinosaur-l@usc.edu
Subject: Re: [dinosaur] Spinosaurus tail propelled swimming locomotion

 

From The Theropod Database-

 

unnamed baryonychine (Hone et al., 2010)
Middle Santonian, Late Cretaceous
Majiacun Formation, Henan, China
Material- (XMDFEC V0010) tooth (52x15x9 mm)
Reference- Hone, Xu and Wang. 2010. A probable baryonychine (Theropoda: Spinosauridae) tooth from the Upper Cretaceous of Henan Province, China. Vertebrata PalAsiatica. 48, 19-26.

 

unnamed Baryonychinae (Candeiro, Abranches, Abrantes, Avilla, Martins, Moreira, Torres and Bergqvist, 2004)
Turonian-Santonian, Late Cretaceous
Adamantina Formation of the Bauru Group, Brazil
Material- (UFRJ-DG 354-Rd) tooth (8.6x5.6x? mm)
(UFRJ-DG 372-Rd) tooth (18.9x10.6x? mm)
Comments- These were assigned to Spinosauridae by Candeiro et al. (2004), but reassigned to Theropoda indet. by Candeiro et al. (2006) because other theropods also have serrationless teeth. However, their round cross section, lack of recurvature and present but tiny serrations (contra Candeiro et al., 2006) indicates they are baryonychine spinosaurids.
References- Candeiro, Abranches, Abrantes, Avilla, Martins, Moreira, Torres and Bergqvist, 2004. Dinosaur remains from western Sao Paulo State, Brazil (Bauru Basin, Adamantina Formation, Late Cretaceous). Journal of South American Earth Sciences. 18, 1-10.
Candeiro, Martinelli, Avilla and Rich, 2006. Tetrapods from the Upper Cretaceous (Turonian-Maastrichtian) Bauru Group of Brazil: A reappraisal. Cretaceous Research. 27, 923-946.

Spinosaurus Stromer, 1915
= Sigilmassasaurus Russell, 1996
S. aegyptiacus Stromer, 1915
= Sigilmassasaurus brevicollis Russell, 1996
= Spinosaurus marocannus Russell, 1996
Turonian-Santonian, Late Cretaceous
Turkana Grits, Kenya
? material (Weishampel, 1990)
Reference- Weishampel, 1990. Dinosaurian distribution. In Weishampel, Dodson and Osmolska (eds.). The Dinosauria. University of California Press, Berkeley. 63-139.

Since African latest Cretaceous records are so terrible, I wouldn't be surprised if we find spinosaurids were still there.  Still it is odd that our last records are from the Santonian in three different continents, and Brazil and China DO have good latest Cretaceous records.  Is there a possibility they did evolve to be basically shoreline animals, so would no longer be expected in the terrestrial formations where we find titanosaurs and abelisaurs?  Are there any good shoreline formations from e.g. Campanian-Maastrichtian South America?

 

Mickey Mortimer

 

 

 

From: dinosaur-l-request@mymaillists.usc.edu <dinosaur-l-request@mymaillists.usc.edu> on behalf of Tim Williams <tijawi@gmail.com>
Sent: Friday, May 1, 2020 10:41 PM
To: dinosaur-l@usc.edu <dinosaur-l@usc.edu>
Subject: Re: [dinosaur] Spinosaurus tail propelled swimming locomotion

 

It goes without saying that this is a spectacular discovery.   A trivial observation: not only is _Spinosaurus_ among the largest known theropods (arguably, *the* largest known theropod), it is also now the largest known aquatic dinosaur.  It blows the largest aquatic birds (hesperornithids, stem-penguins, plotopterids, etc) out of the water, by orders of magnitude.

 

I can't be the only person to wonder that, if spinosaurids continued into the latest Cretaceous, would they have become even more specialized for aquatic habits, similar to mosasaurs or thalattosuchians?  At the moment this is pure speculation; to my knowledge, there is currently no evidence of post-Cenomanian spinosaurids.

 

 

 

On Thu, Apr 30, 2020 at 1:38 AM Ben Creisler <bcreisler@gmail.com> wrote:

 

Ben Creisler

 

A new paper. The paper itself is paywalled but the supplementary stuff is free.

 

Nizar Ibrahim, Simone Maganuco, Cristiano Dal Sasso, Matteo Fabbri, Marco Auditore, Gabriele Bindellini, David M. Martill, Samir Zouhri, Diego A. Mattarelli, David M. Unwin, Jasmina Wiemann, Davide Bonadonna, Ayoub Amane, Juliana Jakubczak, Ulrich Joger, George V. Lauder & Stephanie E. Pierce (2020)
Tail-propelled aquatic locomotion in a theropod dinosaur.
Nature (advance online publication)
DOI: https://doi.org/10.1038/s41586-020-2190-3
https://www.nature.com/articles/s41586-020-2190-3



In recent decades, intensive research on non-avian dinosaurs has strongly suggested that these animals were restricted to terrestrial environments. Historical proposals that some groups, such as sauropods and hadrosaurs, lived in aquatic environments were abandoned decades ago. It has recently been argued that at least some of the spinosaurids--an unusual group of large-bodied theropods of the Cretaceous era--were semi-aquatic, but this idea has been challenged on anatomical, biomechanical and taphonomic grounds, and remains controversial. Here we present unambiguous evidence for an aquatic propulsive structure in a dinosaur, the giant theropod Spinosaurus aegyptiacus. This dinosaur has a tail with an unexpected and unique shape that consists of extremely tall neural spines and elongate chevrons, which forms a large, flexible fin-like organ capable of extensive lateral excursion. Using a robotic flapping apparatus to measure undulatory forces in physical models of different tail shapes, we show that the tail shape of Spinosaurus produces greater thrust and efficiency in water than the tail shapes of terrestrial dinosaurs and that these measures of performance are more comparable to those of extant aquatic vertebrates that use vertically expanded tails to generate forward propulsion while swimming. These results are consistent with the suite of adaptations for an aquatic lifestyle and piscivorous diet that have previously been documented for Spinosaurus. Although developed to a lesser degree, aquatic adaptations are also found in other members of the spinosaurid clade, which had a near-global distribution and a stratigraphic range of more than 50 million years, pointing to a substantial invasion of aquatic environments by dinosaurs.

 

==


Video:


A swimming dinosaur: The tail of Spinosaurus

 

****

News:

 

Virus-free. www.avg.com