Synchrotron X‐ray micro‐computed tomography enhances our knowledge of the skull anatomy of a Late Triassic ecteniniid cynodont with hypercanines

The Anatomical Record, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 13, 2025

Abstract Hypercanines, or hypertrophied canines, are observed in a wide range of both extinct and extant synapsids. In non‐mammaliaform cynodonts, the Permo‐Triassic forerunners mammals, long canines not uncommon, appearing several unrelated taxa within clade. Among them is Trucidocynodon riograndensis , carnivorous ecteniniid cynodont from Late Triassic Brazil, which exhibits specialized dentition, including spear‐shaped incisors, very narrow sectorial postcanines with distally oriented cusps, all have finely serrated margins. Recent synchrotron X‐ray micro‐computed tomography large specimen (CAPPA/UFSM 0029; Várzea do Agudo site, Brazil) provides new insights into its lower jaw as well offers first digital endocast an ecteniniid. Our study reveals presence (i) putatively opened‐root adult stage possible unresorbed remnant old canine, may indicate that stopped replacing canines; (ii) longer than upper and, occlusion, were kept inside deep paracanine fossae perforated dorsal surface rostrum; (iii) diastema between incisors absent holotype; (iv) advanced brain structures, such absence pineal body, cerebral hemispheres divided by interhemispheric sulcus expanded laterally, higher encephalization quotient prozostrodonts, reflecting homoplastic evolution relative sizes lineages. Finally, abundance omnivorous species at where was found—including archosauriforms Dynamosuchus collisensis Stenoscelida aurantiacus —suggests diverse predator guild warrants further investigation paleoecological perspective.

Language: Английский

---

Combined Ca, Sr isotope and trace element analyses of Late Cretaceous dinosaur teeth: assessing diet versus diagenesis

Geochimica et Cosmochimica Acta, Journal Year: 2025, Volume and Issue: unknown

Published: May 1, 2025

Language: Английский

---

Untangling the tree or unravelling the consensus? Recent developments in the quest to resolve the broad-scale relationships within Dinosauria

Journal of Systematic Palaeontology, Journal Year: 2024, Volume and Issue: 22(1)

Published: June 5, 2024

The phylogenetic relationships of the major lineages within Dinosauria have come under intense scrutiny in recent years. In 2017, a radical new hypothesis early dinosaur evolution, 'Ornithoscelida hypothesis', was proposed, prompting flurry work this area. However, instead untangling tree dinosaurs as hoped, further research unravelled scientific consensus on origins and their relationships. Multiple hypotheses now been including several that position 'traditionally' non-dinosaurian silesaurids Dinosauria. There is no sign an emerging consensus, with all possible combinations three clades (Ornithischia, Theropoda Sauropodomorpha) having recovered by analyses. existence 'wildcard taxa' uncertain affinities around base complicates efforts to differentiate these hypotheses. Recent studies suggested data sets used investigate might be fatally flawed. construction stronger focus logical underpinning characters, addition inclusion newly described or redescribed taxa, will likely hold key resolving debate.

Language: Английский

---

The macroecology of Mesozoic dinosaurs

Biology Letters, Journal Year: 2024, Volume and Issue: 20(11)

Published: Nov. 1, 2024

Dinosaurs thrived for over 160 million years in Mesozoic ecosystems, displaying diverse ecological and evolutionary adaptations. Their ecology was shaped by large-scale climatic biogeographic changes, calling a ‘deep-time’ macroecological investigation. These factors include temperature fluctuations the break up of Pangaea, influencing species richness, diversity history. Recent improvements dinosaur fossil record have enabled studies their responses to tectonic, geographic shifts. Trends diversity, body size reproductive traits can now be analysed using quantitative approaches like phylogenetic comparative methods, machine learning Bayesian inference. patterns sometimes align with, but also deviate from, first-order rules (e.g. species–area relationship, latitudinal biodiversity gradient, Bergmann’s rule). Accurate reconstructions palaeobiodiversity niche partitioning require ongoing taxonomic revisions detailed anatomical descriptions. Interdisciplinary research combining sedimentology, geochemistry palaeoclimatology helps uncover environmental conditions driving Fieldwork under-sampled regions, particularly at extremes, is crucial understanding spatial heterogeneity ecosystems across planet. Open science initiatives online databases play key role advancing this field, enriching our deep-time processes, offering new insights into macroecology its broader implications.

Language: Английский

---

Breaking through the eggshell: embryonic development of the premaxillary dentition in Lacerta agilis (Squamata: Unidentata) with special emphasis on the egg tooth

Zoological Journal of the Linnean Society, Journal Year: 2024, Volume and Issue: 201(4)

Published: Aug. 1, 2024

Abstract The egg tooth of squamates is a true that allows them to break, tear, or cut the eggshell during hatching. In this clade there are some uncertainties concerning implantation geometry, number germs, and their fates embryonic development. Here, we used X-ray microtomography light microscopy, focusing on remaining premaxillary teeth sand lizard (Lacerta agilis, Squamata: Unidentata). developing species passes through all classic stages We did not find any evidence large size related merging two which has recently been suggested occur in snakes. Instead, feature can be attributed delayed formation neighbouring regular teeth. This might provide more resources tooth. At last developmental stage, large, midline structure, bent forward as most oviparous Unidentata. It characterized by pleurodont implantation, its base attached pleura peculiar ridge alveolar bone. attachment tissue contains periodontal ligament-like tissue, acellular cementum-like

Language: Английский

---

First Sauropodomorpha (Dinosauria) for the Vila Botucaraí site (Hyperodapedon Assemblage Zone, Candelária Sequence), Rio Grande do Sul, Brazil

Journal of South American Earth Sciences, Journal Year: 2024, Volume and Issue: 140, P. 104927 - 104927

Published: May 6, 2024

Language: Английский

---

Inferring the locomotor ecology of two of the oldest fossil squirrels: influence of operationalization, trait, body size and machine learning method

Proceedings of the Royal Society B Biological Sciences, Journal Year: 2024, Volume and Issue: 291(2034)

Published: Nov. 1, 2024

Correlations between morphology and lifestyle of extant taxa are useful for predicting lifestyles extinct relatives. Here, we infer the locomotor behaviour Palaeosciurus goti from middle Oligocene feignouxi lower Miocene France using their femoral different machine learning methods. We used two ways to operationalize morphology, in form a geometric morphometric shape dataset multivariate 11 traits. The predictive models were built tested more than half (180) species squirrel Both traditional such as linear discriminant analysis sophisticated like neural networks had greatest power. However, power also depended on operationalization traits build model. found that tended improve with increasing body size. Contrary previous suggestions, older species, P. goti, was most likely arboreal, whereas terrestrial. This provides further evidence arboreality already common ecology among earliest squirrels, while predominantly terrestrial evolved shortly afterwards, before vast establishment grasslands Europe.

Language: Английский

---

On a skeletally immature individual of Unaysaurus tolentinoi (Dinosauria: Sauropodomorpha) from the upper Triassic of southern Brazil

The Anatomical Record, Journal Year: 2023, Volume and Issue: 307(4), P. 1071 - 1083

Published: July 6, 2023

Abstract The lineage of sauropodomorph dinosaurs raised some the most impressive animals that ever walked on Earth. However, massive titans Mesozoic Era originated from far smaller dinosaurs. Triassic beds Brazil yielded earliest part this evolutionary history. Despite diverse fossil record early sauropodomorphs, juvenile specimens, as well certain species are poorly sampled. This is case for Unaysaurus tolentinoi , an unaysaurid Caturrita Formation (ca. 225 Ma; Norian, Late Triassic). holotype and only specimen U. was excavated Água Negra Locality (São Martinho da Serra, Rio Grande do Sul, Brazil) in 1998. More than two decades later, no other vertebrates have been reported same fossiliferous site. Here we describe a skeletally immature which found association with . discovered after first‐hand examination comprises isolated vertebrae elements posterior autopodium. According to linear regressions, its metatarsal I approximately 41.7 mm length, compared 75.9 holotype. repeated reduced size indicates it does not belong originally used erect Rather, assigned by topotypy shared morphology. In addition size, distinct lines evidence (e.g., neurocentral sutures; bone texture) support assignment individual. sum, new material expands represents additional dinosaur Formation.

Language: Английский

---

Assessing predator–prey interactions during the Late Triassic of India from bite marks on Hyperodapedon (Archosauromorpha, Rhynchosauria)

Journal of Vertebrate Paleontology, Journal Year: 2024, Volume and Issue: 44(1)

Published: Jan. 2, 2024

Multiple cranial and mandibular remains of Hyperodapedon huxleyi known from the lower part Upper Triassic Maleri Formation were examined to reveal distinct bite marks. These identified as punctures based on their circular or oval elliptical outline deep penetration into cortical bone, found associated with several bone-damaging features such radiating fractures, serrated boundaries, collapsed bony surface. In addition, traces drag marks in form parallel grooves U-shaped cross sections are identified. The compared dental morphology varied Late carnivores India, probable producers suggested be phytosaurs dinosauriforms. trophic structure food web is reconstructed interconnectedness between different animal groups, unconfined feeding habits animals where predators inclined towards opportunistic rather than a niche-based dietary habit. study highlights significance reconstruction ancient paleoecosystems.

Language: Английский

---

Evolution and functional implications of stinger shape in ants

Evolution, Journal Year: 2024, Volume and Issue: unknown

Published: Oct. 5, 2024

Trait diversification is often driven by underlying performance tradeoffs in the context of different selective pressures. Evolutionary changes task specialization may influence how species respond to and alter diversification. We conducted this study investigate functional morphology, evolutionary history, tempo mode evolution Hymenoptera stinger using Ectatomminae ants as a model clade. hypothesized that tradeoff surface underlies diversity morphology shifts between predatory omnivorous diets mediate dynamics trait. Shape variation was characterized X-ray microtomography, correlation shape average values von Mises stress, measure yield failure criteria under loading conditions typical puncture scenarios, determined finite element analysis. observed elongation most but found no evidence biomechanical characteristics measured. Additionally, omnivores have increased phenotypic accelerated metrics, suggesting dietary flexibility releases selection pressure on specific function, resulting greater rate. These results increase our understanding basis shape, indicate not outcome simple optimization, reveal connections diet trait

Language: Английский

---