The late Miocene caimanine fauna (Crocodylia: Alligatoroidea) of the Urumaco Formation, Venezuela

Scheyer, Torsten M.; Delfino, Massimo

doi:10.26879/657

Cited by 18 publications

(38 citation statements)

References 19 publications

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“…2C) from the late Miocene Solimões Formation of Brazil that may be more closely related to M. amazonensis for sharing with this species the same morphology of the jugals. This taxonomic perspective of UFAC-1424 is distinct from those of the holotype and other described specimens of M. nativus , which consist solely of isolated skull tables (see Gasparini, 1985, Cidade et al, 2013 and Scheyer et al, 2013) and can be assigned to M. arendsi following Scheyer & Delfino (2016). Further studies are required to settle the taxonomic assignment of UFAC-1424; in this paper, this specimen is considered as a potential distinct form of Mourasuchus and was used for morphological comparisons and included in the phylogenetic analysis.…”

Section: Methodsmentioning

confidence: 83%

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A newMourasuchus(Alligatoroidea, Caimaninae) from the late Miocene of Venezuela, the phylogeny of Caimaninae and considerations on the feeding habits ofMourasuchus

Cidade

Solórzano

Rincón

et al. 2017

PeerJ

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Mourasuchus (Alligatoroidea, Caimaninae) is one of the most peculiar crocodyliforms due to the skull morphology consisting of a long, wide, dorsoventrally flat rostrum with long, slender mandibular rami. Despite these peculiarities, the systematics, phylogeny and feeding habits of this taxon have not been properly studied. In this paper, we describe a new species of the genus, Mourasuchus pattersoni sp. nov., from the late Miocene of the Urumaco Formation of Venezuela. The new species differs from the other Mourasuchus species in having a lateromedially wide, dorsoventrally high jugal bone and a circular incisive foramen, which both represent autapomorphies of the new taxon. Phylogenetically, M. pattersoni sp. nov. is more closely related to M. amazonensis and the specimen UFAC-1424 (formely attributed to M. nativus) than to M. arendsi or M. atopus, whilst Mourasuchus is recovered once more as a monophyletic group. Furthermore, the cladistic analysis performed in this contribution offers a new phylogenetic assessment of Caimaninae, including many taxa described recently for the group. In this study, we also discuss the crocodylian diversity of the Urumaco Formation as well as how paleoenvironment may have contributed toward its evolution. In addition, we provide a discussion of the potential feeding habits of Mourasuchus. In this contribution, Mourasuchus is regarded as a taxon that likely preferred to prey on small animals. The unusual skull morphology of this group may have evolved to cover a large area with the rostrum, allowing for a more efficient prey capture, while the prey may have consisted predominantly of large amounts of small animals.

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Section: Methodsmentioning

confidence: 83%

“…In particular for Mourasuchus , this geologic unit already had occurrences of the species M. arendsi (Bocquentin-Villanueva, 1984; Scheyer & Delfino, 2016). The description of the new taxon Mourasuchus pattersoni sp.…”

Section: Discussionmentioning

confidence: 99%

A newMourasuchus(Alligatoroidea, Caimaninae) from the late Miocene of Venezuela, the phylogeny of Caimaninae and considerations on the feeding habits ofMourasuchus

Cidade

Solórzano

Rincón

et al. 2017

PeerJ

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“…Together with Globidentosuchus brachyrostris , Caiman australis Bravard, ; Bona and Barrios, , Caiman brevirostris Souza‐Filho, , Caiman gasparinae Bona and Carabajal, , Caiman lutescens Rovereto, , Caiman wannlangstoni Salas‐Gismondi et al, , Gnatusuchus pebasensis Salas‐Gismondi et al, , Kuttanacaiman iquitosensis Salas‐Gismondi et al, , Mourasuchus arendsi Bocquentin‐Villanueva, , Purussaurus mirandai Aguilera, Riff, and Bocquentin‐Villanueva, , Paleosuchus sp. Gray, , Purussaurus brasiliensis Barbosa‐Rodrigues, (see Salas‐Gismondi et al, ; Scheyer & Delfino, ; Scheyer et al, ), Melanosuchus is a component of the high caimanine diversity that evolved in Amazonia since the Late Miocene.…”

Section: Discussionmentioning

confidence: 99%

“…(see Bona et al, in press). The morphometric analyses reveal that MCNC 243 is nested at the margin of the Melanosuchus niger morphospace, and has a relatively robust morphology for its size (see also AMU-CURS-234) (Scheyer & Delfino, 2016), which is the only character of the original diagnosis from Medina (1976) that is actually present in this specimen. However, treating the robust- Melanosuchus and C. latirostris (see above), where Melanosuchus is nested within the genus Caiman (Brochu, 1999(Brochu, , 2004(Brochu, , 2011Hastings et al, 2016;Poe, 1996).…”

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confidence: 87%

“…In consequence, differences in cranial shape are simply given by size, which depends on the length (i.e., the duration of growth, found in dorsal and lateral view) and the starting point of the trajectories (i.e., the size of the hatchling, found only in dorsal view (Brochu, 1999(Brochu, , 2004(Brochu, , 2011Hastings, Reisser, & Scheyer, 2016;Poe, 1996). MCNC 243 shares with M. niger and C. latirostris some discrete characters (or rather falls within the intraspecific morphological range of variation of the two extant taxa) that include: presence of 13 maxillary teeth and a strong transversal preorbital ridge (Scheyer & Delfino, 2016) (also present in C. crocodilus).…”

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confidence: 96%

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Cranial shape variation in jacarean caimanines (Crocodylia, Alligatoroidea) and its implications in the taxonomic status of extinct species: The case of Melanosuchus fisheri

Foth

Blanco

Bona

et al. 2017

Journal of Morphology

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Melanosuchus niger (Crocodylia, Alligatoroidea) is one of the six living caimanine species widely distributed throughout the Amazon River basin today. Although there is only one extant species of Melanosuchus, fossil material assigned to this genus, represented by M. fisheri, has been reported from the late Miocene in South America. However, the validity of this taxon has been questioned and a recent investigation indicates that the referred specimen of M. fisheri (MCZ 4336) actually belongs to Globidentosuchus brachyrostris, while those diagnostic characters present in the holotype (MCNC 243) fall into the spectrum of intraspecific variation of M. niger. Here, we compare the skull shape of the holotype of M. fisheri with the ontogenetic series of the four jacarean species (M. niger, Caiman yacare, Caiman crocodilus, and Caiman latirostris) using 2D-geometric morphometric analyses in two different views. The analyses indicate that MCNC 243 falls into the morphospace of M. niger and C. latirostris. Despite strong shape similarities between juveniles of C. latirostris and MCNC 243, further anatomical comparisons reveal notable differences between them. In contrast, no concrete anatomical differences can be found between MCNC 243 and M. niger, although shape analyses indicate that MCNC 243 is relatively robust for its size. Thus, this study is able to confirm that the genus Melanosuchus was present in the late Miocene, but it still remains unclear if MCNC 243 should be treated as a junior synonym or probably a sister species of M. niger. Its Miocene age favors the second option, but as the shape analyses were also not able to extract any diagnostic characters, it should be retained as Melanosuchus cf. niger.

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Cranial anatomy of Acynodon adriaticus and extreme durophagous adaptations in Eusuchia (Reptilia: Crocodylomorpha)

Muscioni,

Chiarenza,

Fernandez

et al. 2024

The Anatomical Record

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Acynodon adriaticus, a small eusuchian from the Late Cretaceous of Italy, is known for its well‐preserved cranial and postcranial material. Despite its excellent preservation, many details remain hidden due to the physical overlap between the elements and matrix obliteration. We used Micro‐CT scans to reveal previously overlooked anatomical features and describe in detail the cranial and dental anatomy of this taxon, shedding new light on its palaeoecology. The holotypic specimen, SC 57248, represents a mature individual exhibiting signs of hyperossification, developed ornamentation, and various pathologies, including jaw arthritis and a possible dental anomaly. Acynodon adriaticus exhibits significant durophagous adaptations, including a robust, brevirostrine skull optimized for powerful biting and stress‐load capacity. Its specialized dentition, lacking caniniform teeth, features anterior chisel‐like teeth and hypertrophic posterior molariforms with thick enamel, indicative of a diet specializing in hard‐shelled prey. The dentition pattern, accelerated molariform replacement rate, and reduced orbit size suggest adaptations for durophagous foraging in turbid, densely vegetated aquatic environments. The paleoecological context during the Late Cretaceous, characterized by increased freshwater habitats and high invertebrate diversity, likely facilitated the evolution of such specialized traits in A. adriaticus. This small crocodylomorph likely foraged slowly in shallow, benthic environments, using its powerful bite to process mollusks and large arthropods. The study of A. adriaticus, along with comparisons with other crocodylomorphs and ecomorphologically similar taxa like Iharkutosuchus makadii and Gnatusuchus pebasensis, provides a valuable morphofunctional model for understanding the evolutionary pathways of extinct crocodylians to durophagy.

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The late Miocene caimanine fauna (Crocodylia: Alligatoroidea) of the Urumaco Formation, Venezuela

Cited by 18 publications

References 19 publications

A newMourasuchus(Alligatoroidea, Caimaninae) from the late Miocene of Venezuela, the phylogeny of Caimaninae and considerations on the feeding habits ofMourasuchus

A newMourasuchus(Alligatoroidea, Caimaninae) from the late Miocene of Venezuela, the phylogeny of Caimaninae and considerations on the feeding habits ofMourasuchus

Cranial shape variation in jacarean caimanines (Crocodylia, Alligatoroidea) and its implications in the taxonomic status of extinct species: The case of Melanosuchus fisheri

Cranial anatomy of Acynodon adriaticus and extreme durophagous adaptations in Eusuchia (Reptilia: Crocodylomorpha)

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