Epidermal scale growth, allometry and function in non‐avian dinosaurs and extant reptiles

Journal of Anatomy, Journal Year: 2025, Volume and Issue: unknown

Published: March 18, 2025

Abstract Epidermal scales in sauropsids perform a wide array of biological functions, which can relate to their shape and size. Accordingly, growth‐related changes scale morphology may reflect distinct functions between juvenile adult individuals, such as use mating interactions. Such patterns are poorly explored both extant reptiles non‐avian dinosaurs, limiting functional interpretations. Here, we investigate growth the ornithischian ceratopsid Chasmosaurus belli hadrosaurid Prosaurolophus maximus by comparing morphologies juveniles adults each taxon. Scale is generally consistent across stages taxa, C. feature length cannot reject isometry. However, there greater increase width. In practical terms, magnitude these size differences rejects hypothesis that played role interactions, suggesting instead was largely non‐adaptive. To contextualise sampled assessed allometry using an ecologically diverse sample eight reptile species belonging Crocodylidae, Scincidae, Elapidae Pythonidae. While isometry overall most frequent pattern our reptiles, demonstrate positive at least one area bodies, likely response changing body proportions. shapes studied species, retained through growth. This study provides first detailed assessment skin supporting morphological stasis scales.

Language: Английский

---

Complex macroevolutionary dynamics underly the evolution of the crocodyliform skull

Proceedings of the Royal Society B Biological Sciences, Journal Year: 2021, Volume and Issue: 288(1954), P. 20210919 - 20210919

Published: July 13, 2021

All modern crocodyliforms (alligators, crocodiles and the gharial) are semi-aquatic generalist carnivores that relatively similar in cranial form function. However, this homogeneity represents just a fraction of variation once existed clade, which includes extinct herbivorous marine forms with divergent skull structure Here, we use high-dimensional three-dimensional geometric morphometrics to quantify whole-skull morphology across fossil untangle factors shaped macroevolutionary history low phenotypic clade through time. Evolutionary modelling demonstrates pace crocodyliform evolution is initially high, particularly Notosuchia, but slows near base Neosuchia, late burst rapid crown-group crocodiles. Surprisingly, crocodiles, especially Australian, southeast Asian, Indo-Pacific species, have high rates evolution, despite exhibiting variation. Thus, extant lineages not evolutionary stasis rather rapidly fluctuated within limited region morphospace, resulting significant convergence. The structures related jaw closing bite force production (e.g. pterygoid flange quadrate) highly variable, reinforcing importance function driving Together, these findings illustrate apparent conservativeness skulls betrays unappreciated complexity their dynamics.

Language: Английский

---

Lokiceratops rangiformis gen. et sp. nov. (Ceratopsidae: Centrosaurinae) from the Campanian Judith River Formation of Montana reveals rapid regional radiations and extreme endemism within centrosaurine dinosaurs

PeerJ, Journal Year: 2024, Volume and Issue: 12, P. e17224 - e17224

Published: June 20, 2024

The Late Cretaceous of western North America supported diverse dinosaur assemblages, though understanding patterns diversity, evolution, and extinction has been historically limited by unequal geographic temporal sampling. In particular, the existence extent faunal endemism along eastern coastal plain Laramidia continues to generate debate, finer scale regional remain elusive. Here, we report a new centrosaurine ceratopsid, Lokiceratops rangiformis, from lower portion McClelland Ferry Member Judith River Formation in Kennedy Coulee region Canada-USA border. Dinosaurs same small region, nearby, stratigraphically equivalent horizons Oldman Canada, reveal unprecedented ceratopsid richness, with four sympatric taxa one chasmosaurine taxon. Phylogenetic results show that Lokiceratops, together Albertaceratops Medusaceratops, was part clade restricted northern approximately 78 million years ago. This group, Albertaceratopsini, multiple clades undergo geographically radiations, Nasutuceratopsini south Centrosaurini Pachyrostra north. High centrosaurs is associated with, may have driven by, high speciation rates competition between dinosaurs limiting their range. turn sexual selection or latitudinally uneven climatic floral gradients. seen centrosaurines other implies diversity underestimated contrasts large ranges most extant mammalian megafauna.

Language: Английский

---

Ontogenetic dietary shifts in North American hadrosaurids (Dinosauria: Ornithischia)

Cretaceous Research, Journal Year: 2022, Volume and Issue: 135, P. 105177 - 105177

Published: Feb. 23, 2022

Ontogenetic niche shifts, the phenomenon whereby animals change their resource use with growth, were probably widespread in dinosaurs, but most studies of duck-billed dinosaur ontogeny have so far focused mainly on development cranial ornamentation. Here, we quantify allometry 13 ecomorphological variables skull and examine tooth microwear a sample North American hadrosaurids to better understand ecological functioning growth. Our results indicate that, consistent Jarman-Bell principle relating body size fibre intake feeding selectivity, juvenile relatively more selective than adult counterparts subsisted softer, low-growing browse cropped using lateral rotations neck. Chewing movements jaw did not differ greatly between growth stages. findings invite further investigation ontogenetic hadrosauromorphs broadly, possible role shifts structuring Late Cretaceous herbivore communities.

Language: Английский

---

How Triceratops got its face: An update on the functional evolution of the ceratopsian head

The Anatomical Record, Journal Year: 2023, Volume and Issue: 306(7), P. 1951 - 1968

Published: March 8, 2023

Abstract Ceratopsian dinosaurs arguably show some of the most extravagant external cranial morphology across all Dinosauria. For over a century, ceratopsian have inspired multitude functional studies as more discoveries continued to depict larger picture enormous diversity these animals. The iconic horns and bony frills in many ceratopsians portray plethora shapes, sizes, arrangements taxa, their overall feeding apparatus development unique specializations previously unseen large herbivores. Here, I give brief updated review investigating different aspects head. role is explored, with an overview potential for weaponization or defense either intraspecific anti‐predatory combat, among other things. A pertaining also presented here, analyses exploring beak snout morphology, dentition tooth wear, musculature associated skull anatomy, biomechanics.

Language: Английский

---

Dots on a screen: The past, present, and future of morphometrics in the study of nonavian dinosaurs

The Anatomical Record, Journal Year: 2023, Volume and Issue: 306(7), P. 1896 - 1917

Published: March 15, 2023

Using morphometrics to study nonavian dinosaur fossils is a practice that predates the origin of word "dinosaur." By 1970s, linear had become established as valuable tool for analyzing intra- and interspecific variation in dinosaurs. With advent more recent techniques such geometric advanced statistical approaches, morphometric analyses dinosaurs have proliferated, granting unprecedented insight into many aspects their biology evolution. I outline past, present, future applied zeroing on five paleobiology where has been widely utilized advance our knowledge: systematics, sexual dimorphism, locomotion, macroevolution, trackways. Morphometric methods are especially susceptible taphonomic distortion. As such, impact distortion original fossil shape discussed current quantifying accounting with goal reducing noise biological signal ratio. Finally, paleobiologists move "virtual paleobiology" framework, whereby digital renditions captured via photogrammetry computed tomography. These primary data form basis three-dimensional (3D) along slew other forms analyses. 3D specimen part extended help democratize paleobiology, unlocking from physical museum making available researchers across world.

Language: Английский

---

How to tuna fish: constraint, convergence, and integration in the neurocranium of pelagiarian fishes

Evolution, Journal Year: 2023, Volume and Issue: 77(6), P. 1277 - 1288

Published: March 30, 2023

Abstract Morphological evolution of the vertebrate skull has been explored across a wide range tetrapod clades using geometric morphometrics, but application these methods to teleost fishes, accounting for roughly half all species, limited. Here we present results study investigating 3D morphological neurocranium 114 species Pelagiaria, diverse clade open-ocean fishes that includes tuna and mackerel. Despite showing high shape disparity overall, taxa from families fall into three distinct clusters. Convergence in within clusters is high, phylogenetic signal data significant low. Neurocranium significantly correlated with body elongation weakly size. Diet habitat depth are shape, nonsignificant after phylogeny. Evolutionary integration suggesting convergence extreme morphologies associated neurocranial elements. These suggest pelagiarian reflects extremes found constrained along relatively few axes variation, resulting repeated toward restricted morphologies.

Language: Английский

---

Sexual selection leads to positive allometry but not sexual dimorphism in the expression of horn shape in the blue wildebeest, Connochaetes taurinus

BMC Ecology and Evolution, Journal Year: 2022, Volume and Issue: 22(1)

Published: Sept. 11, 2022

Sexual selection is thought to be an important driver of adaptation, speciation and extinction. Empirically testing these predictions across macroevolutionary timescales first requires understanding the morphology secondary sexual traits in extant taxa. We used three-dimensional geometric morphometrics analyse a large sample skull blue wildebeest, Connochaetes taurinus, which horns are found both sexes but only intrasexual competition males. show that fit several traits; overall shape significantly correlated with size (R

Language: Английский

---

Mandibular force profiles of Alioramini (Theropoda: Tyrannosauridae) with implications for palaeoecology of this unique lineage of tyrannosaurid dinosaurs

Lethaia, Journal Year: 2024, Volume and Issue: 57(2), P. 1 - 12

Published: June 20, 2024

Language: Английский

---

Endocranial morphology of three early-diverging ceratopsians and implications for the behavior and the evolution of the endocast in ceratopsians

Paleobiology, Journal Year: 2024, Volume and Issue: unknown, P. 1 - 13

Published: Oct. 30, 2024

Abstract Ceratopsian dinosaurs underwent great changes, including a shift of locomotion mode, enlarged horns and frills, increased body size. These changes occur alongside the evolution endocranial morphology physiology such as size shape flocculus, hearing range, olfactory ratio, reptile encephalization quotient (REQ). However, structures in early ceratopsians is still unclear because lack information on earliest ceratopsians. Here, we reconstructed endocasts three early-diverging Late Jurassic Yinlong , Early Cretaceous Liaoceratops Psittacosaurus . display obvious flocculi, large separate bulbs, long high anterior semicircular canals, relatively cochlear ducts. In to neoceratopsians, include increasing flocculus (which reduced or absent late-diverging ceratopsids), attenuation heightening canal shortened ceratopsids). The suggest had higher acuity were adapted frequencies than Furthermore, REQ suggests that more highly encephalized most extant reptiles. angle lateral heads transition from forward posture downward posture. Our new findings are significant for understanding physiological during ceratopsian also have implications tetrapods.

Language: Английский

---