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RE: [dinosaur] Gryposuchus (Miocene gavialoid) braincase + Cretaceous shark ate turtle + more

I did mean the croc braincase paper.


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-------- Original message --------
From: Ben Creisler <bcreisler@gmail.com>
Date: 01/07/2017 7:35 PM (GMT-05:00)
To: dinosaur-l@usc.edu
Subject: [dinosaur] Gryposuchus (Miocene gavialoid) braincase + Cretaceous shark ate turtle + more

Ben Creisler

Some recent non-dino papers that may be of interest:

Paula Bona, Ariana Paulina Carabajal & Zulma Gasparini (2017)
Neuroanatomy of Gryposuchus neogaeus (Crocodylia, Gavialoidea): a first integral description of the braincase and endocranial morphological variation in extinct and extant gavialoids.
Earth and Environmental Science Transactions of The Royal Society of Edinburgh (advance online publication)
DOI: https://doi.org/10.1017/S1755691016000189

Morphological studies of the braincase and cranial endocast of fossil crocodylians, especially gavialids, are scarce. Here, we present a detailed description of the neuroanatomy of Gryposuchus neogaeus from the Miocene of Argentina, based on CT scans. The cranial endocast is sub-horizontal and the angle formed between the mid-brain and the hind-brain is poorly marked. When compared with Gavialis gangeticus, the mid-brain of G. neogaeus is relatively shorter, although the distribution of cranial nerves is similar. In the floor of the endocranial cavity, posterior to the dorsum sellae, there is a median foramen that leads into a canal that runs anteroventrally through the basisphenoid to penetrate the posterior wall of the pituitary fossa (open foramen for the basilar artery?). The same structure is present in G. gangeticus, but is absent in other living crocodylians, suggesting a potential synapomorphy of Gavialoidea. The pneumaticity of the skull roof and the lateral branches of the pharyngotympanic system in G. neogaeus are markedly reduced when compared with the extant species. Comparisons with the living Gavialis indicate that the pattern of braincase morphology of Gavialidae was present in the Miocene; however, the internal morphology, including brain shape, pneumaticity of the skull roof and basicranium, is different in the two species. This work is the first step to understand the variation of the neuroanatomy in this group of archosaurs and its palaeobiological implication.


Geoffrey A. Manley (2016)

The mammalian Cretaceous cochlear revolution.

Hearing Research (advance online publication)

doi: http://dx.doi.org/10.1016/j.heares.2016.12.007




During the Cretaceous period, major changes occurred in evolving mammalian cochleae.

The loss of the lagenar macula caused a fall in calcium concentrations and a crisis in mammalian hearing abilities.

Prestin evolution was likely the most important result of this crisis, and restored therian hearing levels.


The hearing organs of amniote vertebrates show large differences in their size and structure between the species’ groups. In spite of this, their performance in terms of hearing sensitivity and the frequency selectivity of auditory-nerve units shows unexpectedly small differences. The only substantial difference is that therian, defined as live-bearing, mammalian groups are able to hear ultrasonic frequencies (above 15–20 kHz), whereas in contrast monotreme (egg laying) mammals and all non-mammalian amniotes cannot. This review compares the structure and physiology of the cochleae of the main groups and asks the question as to why the many structural differences seen in therian mammals arose, yet did not result in greater differences in physiology. The likely answers to this question are found in the history of the mammals during the Cretaceous period that ended 65 million years ago. During that period, the therian cochlea lost its lagenar macula, leading to a fall in endolymph calcium levels. This likely resulted in a small revolution and an auditory crisis that was compensated for by a subsequent series of structural and physiological adaptations. The end result was a system of equivalent performance to that independently evolved in other amniotes but with the additional – and of course “unforeseen” - advantage that ultrasonic-frequency responses became an available option. That option was not always availed of, but in most groups of therian mammals it did evolve and is used for communication and orientation based on improved sound localization, with micro-bats and toothed whales relying on it for prey capture.


Jacopo Amalfitano, Fabio Marco Dalla Vecchia, Luca Giusberti, Eliana Fornaciari, Valeria Luciani & Guido Roghi (2017)

Direct evidence of trophic interaction between a large lamniform shark, Cretodus sp., and a marine turtle from the Cretaceous of northeastern Italy.

Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)

doi: http://dx.doi.org/10.1016/j.palaeo.2016.12.044




A specimen of the Upper Cretaceous shark Cretodus is described from northern Italy

The fossil is the most complete specimen of Cretodus so far discovered

The specimen is associated with a pellet-like accumulation of a marine turtle

The turtle remains are interpreted as stomach content of the shark

The fossil represents a direct evidence of possible dietary preferences of Cretodus


In the nineties of the 20th century, a large and partially articulated skeleton of a lamniform shark was discovered in Upper Cretaceous hemipelagic beds of the Venetian Prealps of northeastern Italy. The shark, dating back to the middle Turonian, is here ascribed to Cretodus and represents the first record of this genus in Italy. The fossil is the most complete specimen of Cretodus so far discovered and includes 120 teeth, 86 vertebral centra and many placoid scales. Closely associated with the remains of the shark (estimated total length over 6.5 m) is a pellet-like accumulation of partially broken bones belonging to a large chelonioid turtle (about 2 m of estimated total length). Some of the bones show evidence of damages referable to bites and possible acid etching. Because of this, and because of their position in correspondence of the abdominal region of the shark, the turtle remains are interpreted as stomach content. The taphonomy of this association is discussed and compared with other fossil records of shark predation/scavenging and with lamniform shark-chelonioid turtle interactions in modern marine environment. The Italian fossil represents the second evidence of a turtle swallowed by a shark in the fossil record and a direct evidence of the possible dietary preference of Cretodus, adding some evidence for discerning scavenging from predatory lifestyle.


Sofie Lindström, Bas van de Schootbrugge, Katrine H. Hansen, Gunver K. Pedersen, Peter Alsen, Nicolas Thibault, Karen Dybkjær, Christian J. Bjerrum & Lars Henrik Nielsen (2016)
A new correlation of Triassic–Jurassic boundary successions in NW Europe, Nevada and Peru, and the Central Atlantic Magmatic Province: A time-line for the end-Triassic mass extinction.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
doi: http://dx.doi.org/10.1016/j.palaeo.2016.12.025


A new correlation of Triassic–Jurassic boundary successions is presented.
The new correlation has implications on the causality of the end-Triassic event.
A timeline for the end-Triassic event is constructed.
Onset of the extinction was synchronous to or post-dated the bulk of the CAMP.


Understanding the end-Triassic mass extinction event (201.36 Ma) requires a clear insight into the stratigraphy of boundary sections, which allows for long-distance correlations and correct distinction of the sequence of events. However, even after the ratification of a Global Stratotype Section and Point, global correlations of TJB successions are hampered by the fact that many of the traditionally used fossil groups were severely affected by the crisis. Here, a new correlation of key TJB successions in Europe, U.S.A. and Peru, based on a combination of biotic (palynology and ammonites), geochemical (δ13Corg) and radiometric (U/Pb ages) constraints, is presented. This new correlation has an impact on the causality and temporal development during the end-Triassic event. It challenges the hitherto used standard correlation, which has formed the basis for a hypothesis that the extinction was caused by more or less instantaneous release of large quantities of light carbon (methane) to the atmosphere, with catastrophic global warming as a consequence. The new correlation instead advocates a more prolonged scenario with a series of feedback mechanisms, as it indicates that the bulk of the hitherto dated, high-titanium, quartz normalized volcanism of the Central Atlantic Magmatic Province (CAMP) preceded or was contemporaneous to the onset of the mass extinction. In addition, the maximum phase of the mass extinction, which affected both the terrestrial and marine ecosystems, was associated with a major regression and repeated, enhanced earthquake activity in Europe. A subsequent transgression resulted in the formation of hiati or condensed successions in many areas in Europe. Later phases of volcanic activity of the CAMP, producing low titanium, quartz normalized and high-iron, quartz normalized basaltic rocks, continued close to the first occurrence of Jurassic ammonites and the defined TJB. During this time the terrestrial ecosystem had begun to recover, but the marine ecosystem remained disturbed.


Conrad van den Ende, Lloyd T. White & Peter C. van Welzen (2016)
The existence and break-up of the Antarctic land bridge as indicated by both amphi-Pacific distributions and tectonics.
Gondwana Research (advance online publication)
doi: http://dx.doi.org/10.1016/j.gr.2016.12.006


South America, Australia and Antarctica formed a union till 45 Ma
Many related taxa show a disjunct distribution between South America and Australia
The disjuctions are usually theresult of dispersal/vicariance via Antarctica


Amphi-Pacific disjunct distributions between South America and Australasia are correlated with the breakup and changing palaeo-climate of Gondwana. For a long period, with a temperate climate, Antarctica formed a land bridge between Australia and South America, allowing species to disperse/vicariate between both continents. Dated phylogenies in the literature, showing sister-clades with a distribution disjunction between South America and Australia, were used for the correlation. The initiation of the Antarctic Circumpolar Current, and a change to a colder Antarctic climate is associated with the opening of the Drake Passage between South America and Antarctica at c. 30 Ma, and the final separation of Australia and Antarctica along the South Tasman Rise at c. 45 Ma. The distribution data highlighted the existence of a “southern disjunct distribution” pattern, which may be the result of continental vicariance/dispersal. This is strongly indicative of a connection between Antarctica, South America and Australia; which later provided a dispersal pathway and facilitated vicariance after break up. The taxa that likely dispersed/vicariated via Antarctica included all species with a more (sub)tropical climate preference. Twelve distributions, younger than 30 Ma, are interpreted as the result of long distance dispersal between South America and Australia; these taxa are suited to a temperate climate. The climatic signal shown by all taxa is possibly a consequence of the Australian plate's asynchronous rifting over tens of millions of years in combination with climate changes. These events may have provided opportunities for tropical and sub-tropical species to disperse and speciate earlier than what we observe for the more temperate taxa.