A comprehensive phylogenetic analysis on early ornithischian evolution

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

Published: June 21, 2024

Resolving the evolutionary relationships of early diverging ('basal') ornithischian dinosaurs is a challenging topic in palaeontology, with multiple competing hypotheses on phylogenetic heterodontosaurids, 'hypsilophodontids', and other early-diverging forms. These cannot be directly compared because they are derived from differently constructed datasets (i.e. distinct samples taxa characters). This study aims to address these issues by revising combining into single analysis order create most comprehensive dataset for investigation ornithischians. A diphyletic model Dinosauria supported, silesaurs nesting as members Ornithischia. Heterodontosauridae resolved clade non-genasaurian ornithischians, rejecting potential relationship Marginocephalia. 'Hypsilophodontid' span neornithischian ornithopod stem, Thescelosauridae sister taxon Cerapoda. more restricted Ornithopoda composed five main clades: Hypsilophodontidae, Rhabdodontomorpha, Elasmaria, Dryosauridae Ankylopollexia. Hypsilophodontidae valid clade, reduced two European Barremian taxa. Rhabdodontomorpha does not contain Muttaburrasaurus originally proposed, but instead expands include North American formed Convolosaurus, Iani Tenontosaurus. Elasmaria contains all non-dryomorph Gondwanan ornithopods, its possessing body plans. New results comparison previous studies suggest that some 'true dryosaurids' various euiguanodontians may closely related either or Results group 'hypsilophodontids' larger clades, significantly reducing number extension ghost lineages throughout Neornithischia. clades also show degree endemism, different present at continents Late Cretaceous. new unifying works will provide framework future origins relations attempting find stability among hypotheses.

Language: Английский

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Taxonomic, palaeobiological and evolutionary implications of a phylogenetic hypothesis for Ornithischia (Archosauria: Dinosauria)

Zoological Journal of the Linnean Society, Journal Year: 2022, Volume and Issue: 196(4), P. 1273 - 1309

Published: Aug. 24, 2022

Abstract The origin and evolutionary relationships of ornithischian dinosaurs are topics that have undergone a series substantial revisions. At present there several competing hypotheses concerning the relationship between Ornithischia other principal clades Dinosauria. Some posited tree topology within Dinosauria imply ‘ghost-lineage’ for (whose representatives make their first unambiguous appearance in Hettangian) extends through portion Triassic time. In contrast, placed conventionally dinosauromorph (stem-lineage Dinosauria) taxa clade Ornithischia. Recently, large-scale phylogenetic analysis recovered an array taxa, known as ‘silesaurids’, paraphyletic assemblage (referred to this article using informal terms silesaurs or silesaurians) on branch leading This latter hypothesis would account apparent absence ornithischians, because stem-lineage ornithischians (silesaurs article) exclusively Triassic. However, produced novel used dataset that, its original form, did not include all early (sensu lato), incorporate anatomical characters been suggested unite with dinosaurian (Theropoda Sauropodomorpha). Nor initial study go expand upon some important taxonomic, palaeobiological implications links addresses these issues by expansion re-analysis dataset. results find further support comprise grouping stem successive silesaur acquire anagenetically process culminates assembly what may be described ‘traditional’ ornithischian. overall consensus remains but little changed from analysis, despite addition new characters. To provide stability area preserve most relevant taxonomic names, we suggest revised framework is consistent topology. We retain name total-group (traditional stem-lineage), while resuscitate originally proposed Richard Owen, Prionodontia (= ‘coarse edged teeth’) containing only so-called traditional ‘bird-hipped’) dinosaurs. also erect Parapredentata more exclusive subclade intended clarity degree analyses data continue refine re-shape tree. presented represent stage our attempt establish dinosaur which character definitions scores agreed consistently.

Language: Английский

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A new semi‐fossorial thescelosaurine dinosaur from the Cenomanian‐age Mussentuchit Member of the Cedar Mountain Formation, Utah

The Anatomical Record, Journal Year: 2024, Volume and Issue: 307(12), P. 3717 - 3781

Published: July 9, 2024

Thescelosaurines are a group of early diverging, ornithischian dinosaurs notable for their conservative bauplans and mosaic primitive features. Although abundant within the latest Cretaceous ecosystems North America, record is poor to absent in earlier assemblages, leaving large gap our understanding evolution, origins, ecological roles. Here we report new small bodied thescelosaurine-Fona herzogae gen. et sp. nov.-from Mussentuchit Member Cedar Mountain Formation, Utah, USA. Fona represented by multiple individuals, representing one most comprehensive skeletal assemblages bodied, diverging described from America date. Phylogenetic analysis recovers as earliest member Thescelosaurinae, minimally containing Oryctodromeus, all three species Thescelosaurus, revealing clade was well-established Cenomanian, distinct from, yet continental cohabitants with, sister clade, Orodrominae. To date, orodromines thescelosaurines have not been found together single American ecosystem, suggesting different habitat preferences or competitive exclusion. Osteological observations reveal extensive intraspecific variation across cranial postcranial elements, number anatomical similarities with shared semi-fossorial lifestyle.

Language: Английский

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Early Jurassic origin of avian endothermy and thermophysiological diversity in dinosaurs

Current Biology, Journal Year: 2024, Volume and Issue: 34(11), P. 2517 - 2527.e4

Published: May 15, 2024

A fundamental question in dinosaur evolution is how they adapted to long-term climatic shifts during the Mesozoic and when developed environmentally independent, avian-style acclimatization, becoming endothermic.

Language: Английский

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The phylogenetic relationships and evolutionary history of the armoured dinosaurs (Ornithischia: Thyreophora)

Journal of Systematic Palaeontology, Journal Year: 2023, Volume and Issue: 21(1)

Published: Jan. 1, 2023

The armoured dinosaurs (Thyreophora) were a significant component of Mesozoic terrestrial ecosystems, appearing in the earliest Jurassic and surviving until latest Cretaceous, fossils group have been found on all continents, including Antarctica. However, patchy fossil record highly modified anatomy has hindered reconstruction their evolutionary history. For example, relationships many early-diverging taxa are labile degree convergence between two major clades, Ankylosauria Stegosauria, difficult to assess. There never species-level phylogenetic analysis thyreophoran dinosaurs; recently, computational ability analyse such dataset did not exist and, consequently, interrelationships within debated. Here, we address these issues with new that includes majority named (340 characters, 91 taxa). This was analysed using equal- implied-weights parsimony Bayesian inference, further explored constraint trees partitioned datasets. Stratigraphical congruence used identify 'preferred tree' analyses reveal novel hypothesis for relationships. traditional ankylosaurian dichotomy is supported: instead, four distinct ankylosaur clades identified, long-standing 'traditional' clade Nodosauridae rendered paraphyletic. Ankylosauridae, Panoplosauridae, Polacanthidae Struthiosauridae morphotypes, typified by Euoplocephalus, Edmontonia/Panoplosaurus, Gastonia Struthiosaurus, respectively. Isaberrysaura an early stegosaur Scelidosaurus non-eurypodan. Many characters related feeding quadrupedality coincident diversification Eurypoda. Unstable generally incomplete but other better-known also unstable, suggesting need taxonomic revisions. Partitioned datasets show high postcrania osteoderm do contain strong signal.

Language: Английский

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Anatomical description and digital reconstruction of the skull of Jeholosaurus shangyuanensis (Dinosauria, Ornithopoda) from China

PLoS ONE, Journal Year: 2025, Volume and Issue: 20(1), P. e0312519 - e0312519

Published: Jan. 24, 2025

Ornithopod dinosaurs appeared during the Middle Jurassic, but it was in Lower Cretaceous they started their successful evolutionary history. Different phylogenies describing relationships of Ornithopoda are mostly based on cranial features, however there is a lack well-preserved and complete skulls for basal member clade, hampering our knowledge mode tempo these herbivorous dinosaurs. Here we describe YLSNHM 01942, skull juvenile neornithischian from Liaoning Province China. The specimen scanned with μCT scan, all elements were segmented extrapolated description. shows ventral deformation due to compression sediment, few rostral artificially added. attributed ornithopod Jeholosaurus shangyuanensis because presence large foramen quadratojugal, lacks nodular ornamentation postorbital jugal, herein interpreted as an ontogenetic feature. This, together disarticulation degree elements, suggest 01942 represents . endosseous labyrinth tentatively reconstructed, although neurocranial bones hampers its reconstruction. Thanks analysis previously undescribed inner (such prootics, exoccipital/ophistotic, basioccipital, basisphenoid), improve previous phylogenetical scoring J , perform adding Changmiania liaoningensis recently re-evaluated Ajkaceratops kozmai reports well-supported base Ornithopoda, C most ornithopod, resolved topology Nanosaurus agilis Changchunsaurus parvus Haya griva Yandusaurus hongheensis

Language: Английский

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Intraskeletal histovariability and skeletochronology in an ornithopod dinosaur from the Maestrazgo Basin (Teruel, Spain)

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

Published: Jan. 28, 2025

Abstract Ornithopods are an extinct group of dinosaurs that were particularly abundant and diverse in the Cretaceous Iberian Peninsula, whose abundance Maestrazgo Basin has allowed numerous taxa to be identified over last decade. Many these fossil remains still taxonomically indeterminate require a more detailed study on both macroscopic microscopic scale. In this contribution, osteohistological analysis is carried out partial skeleton—composed five incomplete vertebrae, two dorsal ribs, ischium, fibula, tibia—found province Aliaga (Teruel, NE Spain). We progressive slowdown tissue apposition variation type growth marks generated every bone, allowing precise identification ontogenetic stage specimen as subadult individual. The skeletochronological correlation between different elements also suggests reached sexual maturity at around seven years age died nine twelve age. Likewise, usefulness three‐front model proven for first time ornithopod dinosaur, tool analysing histology expressed by bone single inferring their potential. Comparison with other reveals great variability each element shows depending taxon analysed, which prevents us from determining suitable studying skeletochronology any taxon.

Language: Английский

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Skull morphology and histology indicate the presence of an unexpected buccal soft tissue structure in dinosaurs

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

Published: March 21, 2025

Unlike mammals, reptiles typically lack large muscles and ligaments that connect the zygoma to mandible. Dinosaur craniomandibular soft tissue reconstructions, often based on rationale of extant phylogenetic bracketing, follow this general rule. However, descending flanges from zygomata hadrosaurs, heterodontosaurids, psittacosaurids have been used argue for a masseter-like muscle in these dinosaur taxa. We examined dinosauriform skulls osteological indicators connective entheses mandible, subsequently sectioned 10 specimens histological evidence. Osteological were found most sampled dinosauriforms, which range rugosities processes, morphologically resemble known muscular ligamentous entheses. Similarly, rugose features oriented towards mandible many having previously interpreted as adductor mandibulae group. Serial sectioning ceratopsid, hadrosaurid, tyrannosaurid jugal surangular reveals an external cortex rich collagen fibres, strongly resembling entheseal fibres. Jugal fibres are usually ventrally surangular, hadrosaurids tyrannosaurids parallel macroscopic striations surfaces flange. Histological sections chicken buccal regions show similar attachments jugomandibular ligament musculature hypothesise strong structure bridging dinosaurs, termed 'exoparia'. This structure's size proximity joint would be advantageous stabilising relative cranium during jaw movement, particularly dinosaurs thought process their masticate. A or identity exoparia cannot determined with available data, but shape zygomatic more consistent attachment. Possible antecedents non-dinosauriform archosaurs derivations modern birds may exist, homology is currently unknown. These results highlight complex evolution caution against simplified model-based approaches reconstruction ignore contrasting signals.

Language: Английский

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Ornitópodos basales del centro-sur de Chubut, Patagonia central: Consideraciones evolutivas, paleohistológicas y paleoambientales

Publicación Electrónica de la Asociación Paleontológica Argentina, Journal Year: 2025, Volume and Issue: unknown, P. 31 - 48

Published: April 10, 2025

En el centro-sur de la Provincia Chubut se exponen excelentes afloramientos rocas sedimentarias edad cretácica que conforman principal relleno cuenca del Golfo San Jorge. Dentro esta destacan por su abundancia vertebrados fósiles, Formación Bajo Barreal (Cenomaniano temprano–Turoniano tardío) y Lago Colhué Huapi (Coniaciano–Maastrichtiano). Aunque registro está mayormente dominado dinosaurios saurisquios, hallazgos fósiles ornitisquios, específicamente ornitópodos, han incrementado en los últimos años. contribución pretende ampliar conocimiento ornitópodos basales Notohypsilophodon comodorensis Sektensaurus sanjuanboscoi provenientes las formaciones Huapi, respectivamente. También, primera vez, abordan describen aspectos sobre paleohistología ambos ornitópodos. Asimismo, con evidencias cuentan al momento a espera nuevos estudios resuelvan mejor relaciones sistemáticas base Ornithopoda, sugiere elasmarios habrían originado este Gondwana, probablemente durante Cretácico temprano, posteriormente dispersado oeste dicho supercontinente, donde alcanzaron tamaños corporales mayores. Por último, menos Patagonia central, observa una selección ambiente entre (elasmarios) derivados (hadrosáuridos). Los primeros desarrollado ambientes tierra adentro climas cierta estacionalidad, mientras hadrosáuridos seleccionado cercanos mar un clima más homogéneo.

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A Review of Nanosaurus agilis Marsh and Other Small-Bodied Morrison Formation “Ornithopods”

Bulletin of the Peabody Museum of Natural History, Journal Year: 2025, Volume and Issue: 66(1)

Published: April 25, 2025

Language: Английский

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