Papers by Andrés Solórzano
Historical Biology, Jul 29, 2020
A partial skeleton of Mourasuchus, one of the most peculiar crocodylians of all time, that includ... more A partial skeleton of Mourasuchus, one of the most peculiar crocodylians of all time, that includes cranial and postcranial elements recovered from the late Miocene bone-beds of the Urumaco Formation (northwestern Venezuela) is herein described. Based on the presence of tall squamosal eminences, we assigned it to Mourasuchus arendsi. To provide an empirical assessment of the palaeobiological affinities of Mourasuchus, we performed estimations of the body mass and body length based on several Mourasuchus skull measurements, and an analysis of death roll capability. Our results indicate that Mourasuchus was indeed a large crocodylian, with a body length bigger than 9 m and weighed more than 4 tons. We find that Mourasuchus arendsi was incapable of executing the 'death roll' as a feeding behaviour and as such was unable to predate giant mammals, which are relatively common in the Urumaco Formation. Finally, the specimen includes a slender humerus, which may indicate that Mourasuchus had weak forelimbs and would spend more time in the water.
Historical Biology, Nov 8, 2017
Mourasuchus pattersoni, from the late Miocene Urumaco Formation of Venezuela, is the fourth and m... more Mourasuchus pattersoni, from the late Miocene Urumaco Formation of Venezuela, is the fourth and most recent species described for the genus. The holotype, and only known specimen, is comprised of an almost complete skull with both mandibular rami and several postcranial remains. In ventral view, the right palatine bone has a spherical, nodular bony protuberance located on the anterior portion, near the suture with the maxilla. Unfortunately, we cannot assign a specific diagnosis based only on macroscopic inspection. Its appearance, form and location are compatible with three conditions: torus palatinus, a common benign intraoral bone overgrowth; osteoma, a benign neoplasical overgrowth of the bone; and hamartoma, an overgrowth of normal bone tissue that can only be differed from an osteoma by histological features. While occurrences of torus palatinus or hamartomas are not yet known in the nonhominid vertebrate fossil record, there are previous records of osteomas in fossil vertebrates, including in crocodylians, such as a specimen assigned to 'Crocodylus sp. ' from the Eocene, aside from several records for living crocodylians. Future studies are needed to uncover an accurate diagnosis of this unusual structure and help increase our knowledge of paleopathology in fossil crocodylomorphs in general, especially in the Caimaninae clade.
PeerJ, Mar 7, 2017
Mourasuchus (Alligatoroidea, Caimaninae) is one of the most peculiar crocodyliforms due to the sk... more 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.
MorphoBank datasets, Jan 4, 2021
Historical Biology, 2018
The Miocene crocodyliform fauna of South America is one of the most diverse of the world, and the... more The Miocene crocodyliform fauna of South America is one of the most diverse of the world, and the late Miocene Urumaco Formation of Venezuela has one of its most important assemblages. Mourasuchus (Caimaninae) is one of the most peculiar crocodyliforms of the South American Miocene due to its unusual morphology, which prompted peculiar feeding habits to be proposed for this taxon. In this paper we present a redescription of the holotype of the species Mourasuchus arendsi (CIAAP-1297) from the Urumaco Formation of Venezuela. The redescription offered a thorough reassessment of the skull, mandibles and postcranium that comprise the holotype of M. arendsi, providing a comprehensive morphological description of this specimen for the first time. The data provided by this description prompted a review of the taxonomic status of M. arendsi, which has enabled the possibility of M. arendsi being a junior synonym of M. atopus to be considered and thoroughly discussed in this paper. An eventual confirmation of the synonymy does not change the phylogeny of the Caimaninae clade. This contribution also offers assessments on the ontogenetic status of the holotype of M. arendsi and on the differences on the closure of the scapulocoracoid synchondroses between Mourasuchus specimens.
Journal of Mammalian Evolution, Apr 7, 2016
We report a new genus and species of sloth, based on a partial mandible and associated femur, fro... more We report a new genus and species of sloth, based on a partial mandible and associated femur, from the early Miocene of Venezuela. Baraguatherium takumara, gen. et sp. nov., represents the earliest member of the Mylodontoidea recognized from northern South America. Phylogenetically and morphologically, Baraguatherium possesses some plesiomorphic characters: a vasodentine layer in the core of the tooth similar to Octodontotherium, Paroctodontotherium, and Orophodon; molariforms parallel to the long axis of the toothrow; teeth with a very thin layer of cementum; mf1-mf3 series of similar size and bilobate; mf3 conspicuously piriform; and occlusal surface of tooth beveled, which places it at the base of the Mylodontidae clade. Baraguatherium was found in continental deposits that also preserve abundant wood and leaves associated with a near shore marine complex, indicating that Baraguatherium lived in a coastal tropical forest in the early Miocene in northern South America. The presence of a vasodentine layer in the core of the tooth is quite similar to Octodontotherium, Paroctodontotherium, and Orophodon and allows assignment of this new taxon to the Mylodontoidea.
How to cite Complete issue More information about this article Journal's homepage in redalyc... more How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System
Journal of South American Earth Sciences, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Andean Geology, 2019
The aquatic sloth, Thalassocnus, is one of the most intriguing lineage of mammal known from the s... more The aquatic sloth, Thalassocnus, is one of the most intriguing lineage of mammal known from the southern pacific coast of South America during the late Neogene. It was initially recognized in Perú, but recent paleontological surveys also recorded its presence in Chile. However, the determination of how many species of Thalassocnus were actually present in Chile remains as an open question. Here, we provide a detailed morphological description of an isolated distal fragment of humerus recovered at the Mina Fosforita member (ca. 7 Ma), Bahía Inglesa Formation (Atacama Region, northern Chile), which is referred to Thalassocnus. Morphological comparisons with others forms from Chile and Perú allow us to attribute the CPUC/C/557 specimen to Thalassocnus cf. T. natans, though some degree of intraspecific variation is acknowledged. The assessment of the stratigraphic provenance of the materials with previously assigned to Thalassocnus from the Bahía Inglesa, Horcón and Coquimbo formations,...
Journal of South American Earth Sciences, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Journal of Systematic Palaeontology, 2018
Here we describe two new megalonychid sloths from the late Miocene of the Urumaco Formation (Falc... more Here we describe two new megalonychid sloths from the late Miocene of the Urumaco Formation (Falc on State, Venezuela), Urumacocnus urbanii gen. et. sp. nov. and Pattersonocnus diazgameroi gen. et sp. nov. The recovery of these distinct taxa greatly improves our understanding of sloth diversity in the late Miocene of northern South America. A phylogenetic analysis based on the combination of cranial and postcranial elements (particularly the femur) partially supports previous interpretations of the relationships of genera within the Megalonychidae, but also suggests the existence of a more complex set of subclades within the family in South America, North America and the Antilles.
Palaeobiodiversity and Palaeoenvironments, 2018
Crocodyliform diversity was particularly high during the middle and late Miocene of South America... more Crocodyliform diversity was particularly high during the middle and late Miocene of South America, with up to 12 species recovered from a single geological unit. Nonetheless, the early Miocene fossil record of low-latitude vertebrates is scarce; hence, crocodylians remain poorly known in the region. The Castillo Formation, located in the northwest of Venezuela, preserves an interesting vertebrate fauna with a well-constrained late early Miocene age. Previous work dealing with crocodylians of this formation only recorded three taxa: the gavialoid Siquisiquesuchus venezuelensis and Gryposuchus sp. and indeterminate alligatoroid remains. New cranial and mandibular material recently recovered from the Castillo Formation allows us to document four previously unrecognised alligatoroid forms: Purussaurus sp., Caiman sp., an indeterminate caimanine and an indeterminate alligatoroid. With six taxa, the crocodylian assemblage reveals a previously undocumented relatively high taxonomic diversity in the early Miocene. The Castillo crocodylians show a broad range of morphological disparity and body sizes ranging from small (2.5 m-62 kg) to large (7.5 m-1600 kg) taxa. Thus, crocodylian niche partition, as well as the abundance and variety of resources and environmental heterogeneity of aquatic ecosystems in South America, were already established by at least the early Miocene. The presence of Caiman in~18 Ma strata represents the unequivocally earliest record of the taxon in South America and allows us to propose that the origin of the jacareans is more likely to have occurred during or before the early Miocene, challenging previous molecular hypotheses.
PeerJ, 2017
Mourasuchus (Alligatoroidea, Caimaninae) is one of the most peculiar crocodyliforms due to the sk... more 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 o...
Journal of Human Evolution, 2017
Geobios, 2016
Speech and recital contests are not rare in the language learning landscape of Japan and elsewher... more Speech and recital contests are not rare in the language learning landscape of Japan and elsewhere. However, preparations often neglect important aspects of a good delivery. Too often, student recitals are delivered either in a monotonous fashion with too little attention being paid to segmental phonology and prosody, or highlighting measures like pitch or volume are overused or inappropriately applied. At Aichi Prefectural University a special class has been developed in order to tackle this problem. For this class, a format piloted by Anke Stöver-Blahak at the University of Hanover in Germany has been adapted to the Japanese teaching context. Students are thoroughly familiarised with what is a successful spoken performance. Students are practically introduced to basic aspects of drama pedagogy, phonation, voice coaching, and to simplified concepts of target language (TL) prosody. Further, a strong emphasis is placed on identifying one's audience and adjusting the delivery accordingly. The preliminary 'whys' Becoming more proficient in a language is an arduous multifaceted process that is known to every language learner and language teacher. Improving students' ability in spoken language performance is a major challenge (not only) in Japan (Stephens, 2011). The choice of appropriate content and methodological formats for the situation at hand plays a vital part in this. Mere direct, skill-driven instruction is likely to be insufficient for students to consciously and cognitively acquire the complex systems governing language: that is, the interdependent correlations between grammar, spelling, vocabulary, and prosody when encountering a target language (TL) text. The study of languages in Japan has long been dominated by grammar-translation
Revista Brasileira de Paleontologia, 2016
The Urumaco Formation is well known for being fossiliferous, including both vertebrate and invert... more The Urumaco Formation is well known for being fossiliferous, including both vertebrate and invertebrate assemblages. Despite extensive fi eld work over the past years the decapod fauna from the Urumaco Formation still remains poorly known. In the present work we report for the fi rst time the presence of the extinct portunid crab, Necronectes proavitus Rathbun from Venezuela, based on a well-preserved cast of the carapace recovered from the late Miocene Urumaco Formation. This record signifi cantly contributes to a better understanding of both the biochronology and biogeography of Necronectes in the Caribbean region. N. proavitus is now known from the early to late Miocene of
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Papers by Andrés Solórzano