Paleoecology of Miocene crocodylians in Florida: Insights from stable isotope analysis

Whiting, Evan T.; Steadman, David W.; Krigbaum, John

doi:10.1016/j.palaeo.2016.03.009

Cited by 9 publications

(5 citation statements)

References 88 publications

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“…A recent revision suggests that these fragmentary remains belong to the same lineage as Gavialosuchus eggenburgensis and 'Tomistoma' lusitanica, but that they might represent one or two additional contemporaneous species (Nicholl et al, 2020). The multispecific Thecachampsa is known from abundant remains from the late Oligocene-Miocene of North America (Sellards, 1915;Auffenberg, 1954;Erickson & Sawyer, 1996;Myrick, 2001;Laurito & Valerio, 2008;Whiting, Steadman & Krigbaum, 2016;Weems, 2018). The recovery of Thecachampsa within this clade differs from the results of nearly all previous phylogenetic analyses, which have recovered Gavialosuchus and Thecachampsa as more distantly related members of Tomistominae (e.g.…”

Section: Gavialoideamentioning

confidence: 99%

Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem

Rio

Mannion

2021

PeerJ

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First appearing in the latest Cretaceous, Crocodylia is a clade of semi-aquatic, predatory reptiles, defined by the last common ancestor of extant alligators, caimans, crocodiles, and gharials. Despite large strides in resolving crocodylian interrelationships over the last three decades, several outstanding problems persist in crocodylian systematics. Most notably, there has been persistent discordance between morphological and molecular datasets surrounding the affinities of the extant gharials, Gavialis gangeticus and Tomistoma schlegelii. Whereas molecular data consistently support a sister taxon relationship, in which they are more closely related to crocodylids than to alligatorids, morphological data indicate that Gavialis is the sister taxon to all other extant crocodylians. Here we present a new morphological dataset for Crocodylia based on a critical reappraisal of published crocodylian character data matrices and extensive firsthand observations of a global sample of crocodylians. This comprises the most taxonomically comprehensive crocodylian dataset to date (144 OTUs scored for 330 characters) and includes a new, illustrated character list with modifications to the construction and scoring of characters, and 46 novel characters. Under a maximum parsimony framework, our analyses robustly recover Gavialis as more closely related to Tomistoma than to other extant crocodylians for the first time based on morphology alone. This result is recovered regardless of the weighting strategy and treatment of quantitative characters. However, analyses using continuous characters and extended implied weighting (with high k-values) produced the most resolved, well-supported, and stratigraphically congruent topologies overall. Resolution of the gharial problem reveals that: (1) several gavialoids lack plesiomorphic features that formerly drew them towards the stem of Crocodylia; and (2) more widespread similarities occur between species traditionally divided into tomistomines and gavialoids, with these interpreted here as homology rather than homoplasy. There remains significant temporal incongruence regarding the inferred divergence timing of the extant gharials, indicating that several putative gavialids (‘thoracosaurs’) are incorrectly placed and require future re-appraisal. New alligatoroid interrelationships include: (1) support for a North American origin of Caimaninae in the latest Cretaceous; (2) the recovery of the early Paleogene South American taxon Eocaiman as a ‘basal’ alligatoroid; and (3) the paraphyly of the Cenozoic European taxon Diplocynodon. Among crocodyloids, notable results include modifications to the taxonomic content of Mekosuchinae, including biogeographic affinities of this clade with latest Cretaceous–early Paleogene Asian crocodyloids. In light of our new results, we provide a comprehensive review of the evolutionary and biogeographic history of Crocodylia, which included multiple instances of transoceanic and continental dispersal.

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Section: Gavialoideamentioning

confidence: 99%

Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem

Rio

Mannion

2021

PeerJ

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“…Marine crocodylians were essentially shallow marine inhabitants. These environments have been proposed for several taxa of gavialoids by taphonomic, geologic, and isotopic data [12][13][14][15][16][17][18][19]22,54] and are consistent with their locomotionrelated anatomy. Because marine crocodylians show no significant differences in the axial skeleton and the hindlimbs relative to living forms, they are inferred to have swum by using axial undulatory movements and terrestrial-adapted limbs ( plesiopedal) [55].…”

Section: (D) What Is a Marine Crocodylian?mentioning

confidence: 76%

Miocene fossils from the southeastern Pacific shed light on the last radiation of marine crocodylians

et al. 2022

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The evolution of crocodylians as sea dwellers remains obscure because living representatives are basically freshwater inhabitants and fossil evidence lacks crucial aspects about crocodylian occupation of marine ecosystems. New fossils from marine deposits of Peru reveal that crocodylians were habitual coastal residents of the southeastern Pacific (SEP) for approximately 14 million years within the Miocene ( ca 19 to 5 Ma), an epoch including the highest global peak of marine crocodylian diversity. The assemblage of the SEP comprised two long and slender-snouted (longirostrine) taxa of the Gavialidae: the giant Piscogavialis and a new early diverging species, Sacacosuchus cordovai . Although living gavialids ( Gavialis and Tomistoma ) are freshwater forms, this remarkable fossil record and a suite of evolutionary morphological analyses reveal that the whole evolution of marine crocodylians pertained to the gavialids and their stem relatives (Gavialoidea). This adaptive radiation produced two longirostrine ecomorphs with dissimilar trophic roles in seawaters and involved multiple transmarine dispersals to South America and most landmasses. Marine gavialoids were shallow sea dwellers, and their Cenozoic diversification was influenced by the availability of coastal habitats. Soon after the richness peak of the Miocene, gavialoid crocodylians disappeared from the sea, probably as part of the marine megafauna extinction of the Pliocene.

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“…From the current data at hand, it cannot be ascertained whether Toyotamaphimeia machikanensis strictly inhabited the freshwater environment or whether it also foraged in the nearby marine environment, but Ijima et al (2018) hypothesized repeated dispersals of this genus from mainland Asia into Japan either thanks to a temporary land bridge or through coasting. Other Miocene tomistomines are recovered in estuarine environments with Thecachampsa (Gavialosuchus) americanus from the phosphates of Florida (Mook, 1921), Gavialosuchus eggenburgensis from Austria (Toula and Kail, 1885) or Tomistoma lusitanica (Antunes, 1961) from Portugal (see also Whiting et al, 2016).…”

Section: Distribution and Origin Of Asian Tomistominesmentioning

confidence: 99%

An Eocene tomistomine from peninsular Thailand

Martin

Lauprasert

Tong

et al. 2019

Annales de Paléontologie

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Skull and mandibular elements of a tomistomine crocodilian are described from the late Eocene to early Oligocene lignite seams of Krabi, peninsular Thailand. The Thai tomistomine is a longirostrine form characterized by a rostrum/skull ratio of about 0.6; a mandibular symphysis reaching the level of the eleventh alveolus; a deep participation of the splenial in the symphysis to the level of ninth alveolus; an enlarged fifth maxillary alveolus; long nasals reaching the premaxillae at the level of the fifth maxillary alveolus but not contributing to the external nares; undivided posterior processes of premaxillae; a short prefrontal, excluded by a longer lacrimal from the posteromedial margin of maxillae; vomers visible on the palate. A phylogenetic analysis recovers the Thai specimen among derived tomistomines, on the stem lineage of the extant Tomistoma schlegelii, as a close ally of Maomingosuchus petrolica, a late Eocene tomistomine from southern China. The present recognition of Maomingosuchus sp. in late Eocene Thai deposits expands the distribution of Eocene tomistomines from southern China to the tropics. The origin of Tomistominae in Asia is briefly discussed. Résumé Des éléments crâniens et mandibulaires d'un crocodilien tomistominé sont décrits en provenance de niveaux à lignite de l'Eocène supérieur à Oligocène inférieur de Krabi sur la péninsule Thailandaise. Le tomistominé Thaïlandais est caractérisé par un crâne de type longirostre présentant un ratio rostre/crâne d'environ 0.6 ; une symphyse mandibulaire qui atteint le niveau du onzième alvéole ; une participation profonde du splénial dans la symphyse mandibulaire au niveau du neuvième alvéole ; un cinquième alvéole maxillaire élargi ; les os du nasal qui atteignent les prémaxillaires au niveau du cinquième alvéole maxillaire mais ne participant pas aux narines externes ; des processus postérieurs des prémaxillaires nondivisés ; un préfrontal court, exclu de la marge postéromédiale des maxillaires par un lacrimal plus long ; un vomer visible sur le palais. Une analyse phylogénétique place le spécimenThaïlandais au sein des tomistominés dérivés, au sein de la lignée de l'actuel Tomistoma schlegelii, et proche de Maomingosuchus petrolica, un taxon de la fin de l'Eocène connu en Chine du sud. La présente découverte de Maomingosuchus sp. dans l'Eocène tardif de Thaïlande étend l'aire de répartition des tomistominés eocènes depuis la Chine du sud jusqu'aux tropiques. L'origine des Tomistominae en Asie est brièvement discutée.

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Paleoecology of Miocene crocodylians in Florida: Insights from stable isotope analysis

Abstract: 2016-11-03T14:11:40

Cited by 9 publications

References 88 publications

Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem

Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem

Miocene fossils from the southeastern Pacific shed light on the last radiation of marine crocodylians

An Eocene tomistomine from peninsular Thailand

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