Semi-aquatic adaptations in a spinosaur from the Lower Cretaceous of Brazil

Aureliano, Tito; Ghilardi, Aline Marcele; Buck, Pedro Victor; Fabbri, Matteo; Samathi, Adun; Delcourt, Rafael; Fernandes, Marcelo Adorna; Sander, P. Martin

doi:10.1016/j.cretres.2018.04.024

Cited by 35 publications

(24 citation statements)

References 85 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…However, in tetrapods adapted for a semi-aquatic or entirely aquatic lifestyle, such as marine reptiles like plesiosaurs, marine mammals, marine birds, and even spinosaurid dinosaurs, pachyostosis, the extreme thickening of cortical bone, occurs in the limbs 79–84 . Given that pachyostosis is present in the limb bones of both avian and non-avian theropods that took to the water 84 , the absence of such thickening in Halszkaraptor , which Cau et al . 32 posit was well-adapted for a semi-aquatic ecology, would be very surprising from a biomechanical standpoint.…”

Section: Resultsmentioning

confidence: 99%

Halszkaraptor escuilliei and the evolution of the paravian bauplan

Brownstein

2019

Sci Rep

View full text Add to dashboard Cite

The evolution of birds from dinosaurs is a subject that has received great attention among vertebrate paleontologists. Nevertheless, the early evolution of the paravians, the group that contains birds and their closest non-avian dinosaur relatives, remains very poorly known. Even the most basal members of one paravian lineage, the Dromaeosauridae, already show a body plan that differs substantially from their closest non-paravian relatives. Recently, the dromaeosaurid Halszkaraptor escuilliei was described from the Cretaceous of Mongolia. Halszkaraptor possesses numerous unserrated premaxillary teeth, a platyrostral rostrum with a developed neurovascular system, an elongate neck, bizarrely-proportioned forearms, and a foreword-shifted center of mass, differing markedly from other paravians. A reevaluation of the anatomy, taphonomy, environmental setting, and phylogenetic position of H. escuilliei based on additional comparisons with other maniraptorans suggests that, rather than indicating it was a semiaquatic piscivore, the body plan of this dinosaur bears features widely distributed among maniraptorans and in some cases intermediate between the conditions in dromaeosaurids and related clades. I find no evidence for a semiaquatic lifestyle in Halszkaraptor. A phylogenetic reevaluation of Halszkaraptorinae places it as the sister clade to Unenlagiinae, indicating the bizarre features of unenlagiines previously interpreted as evidence of piscivory may also represent a mosaic of plesiomorphic, derived, and intermediate features. The anatomy of Halszkaraptor reveals that dromaeosaurids still possessed many features found in more basal maniraptoran and coelurosaur clades, including some that may have been tied to herbivory. Rather than being a semiaquatic piscavore, Halszkaraptor was a basal dromaeosaurid showing transitional features.

show abstract

Section: Resultsmentioning

confidence: 99%

Halszkaraptor escuilliei and the evolution of the paravian bauplan

Brownstein

2019

Sci Rep

View full text Add to dashboard Cite

show abstract

“…It is unclear why competition with other theropods (the extent of which is unknown) would have potentially driven the large size of Spinosaurus in the Kem Kem, or any of the other localities across North Africa where it has been recovered. Other large spinosaurines with similar anatomy are known in other localities including those that are older than Spinosaurus (e.g., pachyostotic spinosaurine in Brazil - Aureliano et al, 2018;Ichthyovenator in Laos, Allain et al, 2012), and their evolution would not have been influenced by the ecology of the Kem Kem. Since the presence of multiple large theropods (or indeed vertebrate predators generally) in environments even when exploiting similar prey is normal (Hone et al, 2010), and other spinosaurids are also large, it is not clear why such competition should drive large size in Spinosaurus in particular.…”

Section: Environmental Factorsmentioning

confidence: 96%

“…The spinosaurids are widely regarded as being at least partly piscivorous, and with potential affinities for aquatic habitats (e.g., Charig and Milner, 1995;Bertin, 2010;Cuff and Rayfield, 2013;Hone and Holtz, 2017;Aureliano et al, 2018;Hassler et al, 2018) although this does not exclude other prey or the occupation of other habitats (Bertin, 2010;Amiot et al, 2010a, b;Allain et al, 2012;Hendrickx et al, 2016), and likely took prey from the margins of aquatic habitats. The recent discovery of new and much more complete material has brought new data and with it new hypotheses about the biology of this animal (Ibrahim et al, 2014a(Ibrahim et al, , 2020a.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the ecology of Spinosaurus: shoreline generalist or aquatic pursuit specialist?

Hone

Holtz

2021

Palaeontol Electron

View full text Add to dashboard Cite

The giant theropod Spinosaurus was an unusual animal and highly derived in many ways, and interpretations of its ecology remain controversial. Recent papers have added considerable knowledge of the anatomy of the genus with the discovery of a new and much more complete specimen, but this has also brought new and dramatic interpretations of its ecology as a highly specialised semi-aquatic animal that actively pursued aquatic prey. Here we assess the arguments about the functional morphology of this animal and the available data on its ecology and possible habits in the light of these new finds. We conclude that based on the available data, the degree of adaptations for aquatic life are questionable, other interpretations for the tail fin and other features are supported (e.g., socio-sexual signalling), and the pursuit predation hypothesis for Spinosaurus as a "highly specialized aquatic predator" is not supported. In contrast, a 'wading' model for an animal that predominantly fished from shorelines or within shallow waters is not contradicted by any line of evidence and is well supported. Spinosaurus almost certainly fed primarily from the water and may have swum, but there is no evidence that it was a specialised aquatic pursuit predator.

show abstract

“…While the unique postcranial adaptations of Spinosaurus point towards an entirely novel mode of locomotion in dinosaurs, other spinosaurids share a wide range of derived anatomical features consistent with a partially aquatic, piscivorous mode of life 7,8,11,14,30 . The exact extent to which an aquatic lifestyle was adopted by these other taxa and how this varied across Spinosauridae remains to be established.…”

Section: Morocco (Figs 1 2 Extended Data Figs 1-4 Supplementary mentioning

confidence: 99%

“…A recent reappraisal of the largest known spinosaurid, Spinosaurus aegyptiacus, identified a series of adaptations consistent with a semi-aquatic lifestyle, including reduced hindlimbs, wide feet with large, flat unguals, long bones with a highly reduced medullary cavity, and a suite of cranial features such as retracted nares, interlocking conical teeth, and a rostromandibular integumentary sensory system 7 . This interpretation has been challenged on the basis of taphonomy 8 , biomechanical modeling 10 , and anatomical concerns 8 . Locomotion in water is a major point of contention 10,11 , because no unambiguous evidence for a plausible mode of propulsion has been presented.…”

mentioning

confidence: 99%

Tail-propelled aquatic locomotion in a theropod dinosaur

Ibrahim

Maganuco²,

Sasso³

et al. 2020

Nature

Self Cite

110

View full text Add to dashboard Cite

Intensive research on non-avian dinosaurs in recent decades strongly suggests that these animals were restricted to terrestrial environments 1. Historical views proposing that some groups, such as sauropods and hadrosaurs, lived in aquatic environments 2,3 were abandoned decades ago 4,5,6. Recently, however, it has been argued that at least some spinosaurids, an unusual group of large-bodied Cretaceous theropods, were semi-aquatic 7,8 , but this idea has been challenged on anatomical, biomechanical, and taphonomic grounds and remains controversial 9,10,11. Here we present the first unambiguous evidence for an aquatic propulsive structure in a dinosaur, the giant theropod Spinosaurus aegyptiacus 7, 12. This dinosaur has a tail with an unexpected and unique shape consisting of extremely tall neural spines and elongate chevrons forming a large, flexible, fin-like organ capable of extensive lateral excursion. Using a robotic flapping apparatus to measure undulatory forces in physical tail models, we show that the tail shape of Spinosaurus produces greater thrust and efficiency in water than the tail shapes of terrestrial dinosaurs, comparable to that of extant aquatic vertebrates that use vertically expanded tails to generate forward propulsion while swimming. This conclusion is consistent with a suite of adaptations for an aquatic lifestyle and a piscivorous diet in Spinosaurus 7,13,14. Although developed to a lesser degree, aquatic adaptations are also found in other spinosaurids 15,16 , a clade with a near global distribution and a stratigraphic range of more than 50 million years 14 , documenting a significant invasion of aquatic environments by dinosaurs.

show abstract

Semi-aquatic adaptations in a spinosaur from the Lower Cretaceous of Brazil

Cited by 35 publications

References 85 publications

Halszkaraptor escuilliei and the evolution of the paravian bauplan

Halszkaraptor escuilliei and the evolution of the paravian bauplan

Evaluating the ecology of Spinosaurus: shoreline generalist or aquatic pursuit specialist?

Tail-propelled aquatic locomotion in a theropod dinosaur

Contact Info

Product

Resources

About