Topic
Eocasea
About: Eocasea is a research topic. Over the lifetime, 4 publications have been published within this topic receiving 104 citations.
Papers
TL;DR: An expanded version of a recently published phylogenetic analysis of pelycosaurian-grade synapsids positions Vaughnictis as the sister taxon of Eothyris within the clade Eothirididae, and confirms the recently-disputed position of caseasaurs as the most basal synapsid.
Abstract: ‘Mycterosaurus’ smithae, from the Cisuralian (early Permian) of Colorado, was first described in 1965 as a second species of the genus Mycterosaurus. While the type species of this genus, M. longiceps, has been shown by multiple cladistic analyses to belong to the basal synapsid family Varanopidae, ‘M.’ smithae has been largely ignored since its original description. Additional preparation and synchrotron scanning has revealed new significant information that supports the assignment of this species to a new genus: Vaughnictis gen. nov. Vaughnictis lacks many of the characteristics of mycterosaurines and varanopids in general: it lacks the slender femur, the linguo-labially compressed and strongly recurved teeth, and the lateral boss on the postorbital characteristic of this family. Instead, it possesses coronoid teeth, a large supratemporal, and a large pineal foramen positioned midway along the length of the parietal, features that support its assignment to Eothyrididae. Moreover, the postcranium shares many characters with the eothyridid Oedaleops. An expanded version of a recently published phylogenetic analysis of pelycosaurian-grade synapsids positions Vaughnictis as the sister taxon of Eothyris within the clade Eothyrididae. The addition of data on the postcranium of eothyridids and the inclusion of the recently-described basal caseid Eocasea confirms the recently-disputed position of caseasaurs as the most basal synapsids. As the parsimony analysis produced low support values and a lack of resolution due to missing data, additional analyses were undertaken using Bayesian and Implied Weights methods, which produced better resolution and relationships with higher support values. While the results are similar, alternative positions for the enigmatic Moscovian age (Carboniferous) synapsid Echinerpeton are suggested by Bayesian analysis; the parsimony analysis found it to be an ophiacodontid, while the Bayesian and Implied Weights analysis found it to be the sister to the Sphenacomorpha.
51 citations
TL;DR: The analysis showed a decoupling between the long bones of the fore- and hindlimbs, with the hind leg remaining more conservative and congruent to a basal pattern, and the forelimbs show greater restructuring in the course of evolution, with an allometric strengthening not limited to species of very large size.
Abstract: In this study, the evolution of the long bones in a group of basal synapsids was analysed, belonging to the caseids (Synapsida, Caseasauria, Caseidae), a crucial Palaeozoic group of terrestrial vertebrates. During their evolutionary history, caseids transitioned from small faunivorous tetrapods such as Eocasea martini (reaching ~20 cm total length), to gigantic herbivores such as Cotylorhynchus hancocki (reaching almost 7 m in length). In this analysis, morphometric techniques (i.e. Principal Component Analysis, Reduced Major Axis (regression) slopes) and phylogenetic methods (construction of metric trees) were used in a comparative and integrated way in order to study the major changes in the long bones in the course of caseid evolution, and identify in which nodes and terminal branches more extreme repatterning of structures is concentrated. The analysis showed a decoupling between the long bones of the fore- and hindlimbs, with the hind leg remaining more conservative and congruent to a basal pattern. By contrast, the forelimbs (especially the ulna and radius) show greater restructuring in the course of evolution, with an allometric strengthening not limited to species of very large size. An overbuilt appendicular skeleton was detected as early as taxa small to medium in size, indicating that the strengthening is not related in a simple and linear way to a structural response to gigantic body size. Because this robust structure is already present in small- to medium-sized taxa, it may have been subsequently exapted, allowing to reach the colossal body size of more derived members of Caseidae, which rank among the largest reached throughout the Palaeozoic.
23 citations
TL;DR: These results demonstrate for the first time that large caseid herbivores evolved from small, non-herbivorous caseids, and are mirrored by three other clades, documenting multiple, independent, but temporally staggered origins of herbivory and increase in body size among early terrestrial tetrapods, leading to patterns consistent with modern terrestrial ecosystem.
Abstract: The origin and early evolution of amniotes (fully terrestrial vertebrates) led to major changes in the structure and hierarchy of terrestrial ecosystems. The first appearance of herbivores played a pivotal role in this transformation. After an early bifurcation into Reptilia and Synapsida (including mammals) 315 Ma, synapsids dominated Paleozoic terrestrial vertebrate communities, with the herbivorous caseids representing the largest vertebrates on land. Eocasea martini gen. et sp. nov., a small carnivorous caseid from the Late Carboniferous, extends significantly the fossil record of Caseidae, and permits the first clade-based study of the origin and initial evolution of herbivory in terrestrial tetrapods. Our results demonstrate for the first time that large caseid herbivores evolved from small, non-herbivorous caseids. This pattern is mirrored by three other clades, documenting multiple, independent, but temporally staggered origins of herbivory and increase in body size among early terrestrial tetrapods, leading to patterns consistent with modern terrestrial ecosystem.
TL;DR: A phylogenetic analysis posits the Late Pennsylvanian Eocasea martini Reisz and Fröbisch, 2014, as the basalmost member of the monophyletic Caseidae and the later occurring middle Early Permian Bromacker caseid as the sister taxon of the remaining late Early and Middle Permians members of the clade.
Abstract: A new genus and species of a basal synapsid Caseidae, Martensius bromackerensis, is described based on four partial to nearly complete mostly articulated skeletons that provide a comprehensive knowledge of the skeletal morphology. All four specimens were collected from a single site, the Bromacker quarry, in the Lower Permian Artinskian Tambach Formation, Germany. The Bromacker caseid is the first to be reported from Germany and can be easily distinguished from all other caseids based on substantial lists of autapomorphic and plesiomorphic characters. Of the four caseid specimens only the smallest, a juvenile, and the largest, an adult designated as the holotype, are nearly complete, articulated, and possess skull material: in the juvenile a small partially articulated portion of the skull, and in the adult a nearly complete but dorsoventrally crushed skull. The two specimens are distinguished from one another by features attributed to different ontogenetic stages of development, which include skeletal ossification, proportional dimensions of elements, and most interestingly marginal dentitions. The last category includes a feature unique among caseids of an ontogenetic change in the dentition from insectivorous in the juvenile specimen to what is believed to be an omnivorous dentition in the adult.A phylogenetic analysis posits the Late Pennsylvanian Eocasea martiniReisz and Frobisch, 2014, as the basalmost member of the monophyletic Caseidae and the later occurring middle Early Permian Bromacker caseid as the sister taxon of the remaining late Early and Middle Permian members of the clade. This series of relationships parallels a proposed chronology of evolutionary changes in the dentitions and associated diets of caseids.
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| Year | Papers |
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| 2020 | 1 |
| 2017 | 1 |
| 2016 | 1 |
| 2014 | 1 |