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Principal characters of American Jurassic dinosaurs
... ORNITHOPODA Marsh, 1881 [75] sensu Madzia, Arbour, Boyd, Farke, Cruzado-Caballero, and Evans, 2021 [76]. IGUANODONTIA Dollo, 1888 [77] sensu Madzia, Arbour, Boyd, Farke, Cruzado-Caballero, and Evans, 2021 [76]. ...
Styracosternan ornithopods are plenty abundant in the Lower Cretaceous fossil record of Europe. In particular, Iguanodon, the second genus of dinosaurs described worldwide, has been found in UK, Belgium, France, Germany, and Spain, evidencing a wide geographical distribution. Currently, the genus Iguanodon comprises two species, the type species I. bernissartensis from the late Barremian–Aptian of Europe and I. galvensis from the early Barremian of Teruel, Spain. The latter species is well known mainly from perinate and juvenile specimens. Here, axial and appendicular fossils of an adult, large and massively constructed ornithopod from the lower Barremian (Lower Cretaceous) Camarillas Formation of Galve (province of Teruel, Spain) are described. Fossil dimensions and some osteological evidence reveal that the specimen was a large (roughly 10 m long) ornithopod. An autapomorphic feature in the ischium and other characters allow us to ascribe this specimen to I. galvensis. In addition, postcranial co-ossification and fusion of the neurocentral suture indicate that the specimen was skeletally mature. Part of the material studied here was unknown in adults of I. galvensis, providing a better knowledge of the axial and appendicular region of this species.
... On a nomenclatural note, the authority for Ornithopoda, commonly given to Marsh (1881), is more correctly attributed to Huxley (1870), whose use of the name may be a misspelling of Orthopoda Cope, 1866, but was not interpreted as such by Cope (1871 Reference phylogeny. As for Madzia et al. (2021). ...
... YPM 1980 is the holotype partial skeleton of Brontosaurus excelsus (Marsh, 1879), from Como Bluff. The history and geological setting of the specimen are ably covered elsewhere (e.g., Foster, 2020;Ostrom & McIntosh, 1966, and references therein) and we will not discuss them further. ...
Postcranial pneumaticity is interpreted as a weight saving adaptation in sauropod dinosaurs, especially in the vertebral column. In some derived sauropods pneumatic features also occur on vertebral ribs. While pneumatic ribs are considered diagnostic of the clade Titanosauriformes, they are also infrequently found in diplodocid sauropods. Here, we describe a partial dorsal rib IV or V referable to Apatosaurus sp. that exhibits a series of superficial pneumatic fossae along its posterior surface. These fossae differ from the morphology found in other pneumatic dorsal ribs of diplodocids, including other apatosaurines and Supersaurus. Moreover, the pneumatic features of this rib are more distally located from the capitulum and tuberculum than in other diplodocids and titanosaurs. Based on our findings, we propose that rib pneumaticity among apatosaurine sauropods (and potentially all diplodocids) is individually variable, in addition to being a function of ontogeny. More broadly, we conclude that rib pneumaticity among diplodocids is morphologically variable when present and individually expressed rather than being ubiquitous throughout the clade. Our findings are consistent with the hypothesis that pneumatic ribs evolved independently between Diplodocidae and Titanosauriformes and make for poor clade-level characters among diplodocids.
... It is possible that this misconception arose from the name of the sauropod Diplodocus, which means "double beam," although Diplodocus' name refers to the shape of the chevron bones beneath its tail vertebrae and not to any aspect of its hips. 59 In any case, as we have seen, verse 14 is consistent with the PMA. ...
Zoology and Job 40: Review and critique of the arguments for Behemoth as a dinosaur Job 40:15-24 describes a monstrous creature named Behemoth, whom ancient Jewish literature treats as a supernatural monster. In contrast, much literature of the thirteenth century and later applies a zoological approach, interpreting Behemoth as a species of animal, usually the hippopotamus in publications from 1663 onward. Since 1974, numerous advocates of the zoological approach have reinterpreted Behemoth as a dinosaur, usually a sauropod. Arguments for Behemoth as a sauropod include allegations that Job 40 describes an animal that is herbivorous, aquatic, docile, and indomitable; drinks large amounts of water; has strong bones, strong hips, a bulbous midsection, tight sinews, and a cedar-like tail; and is the largest land animal that God made. Here, I investigate the relative popularity and temporal duration of each such argument and determine which such arguments are based on sound interpretations of the Hebrew text. This investigation reveals that no argument for Behemoth as a dinosaur survives scrutiny. Several, notably including the argument that Behemoth's tail is like a cedar, are based on misinterpretations of the Hebrew text. In contrast, all parts of the Hebrew text are consistent with the interpretation of Behemoth as a primordial, supernatural monster.
Fieldwork in the late 1980s in the Otlaltepec Formation Middle Jurassic (Bathonian-Callovian) of southern Puebla resulted in the recovery of the first osteological record of a Flagellicaudata dinosaur from Mexico and the southern-most for North America. The material is represented by metatarsal fragments of the right pes, showing autapomorphies in metatarsal II for Flagellicaudata. The available material is incomplete and the sample remains small, but it suggests the possible presence of a new taxon. This specimen provides data on the distribution and diversity of sauropod dinosaurs of southern North America during the Middle Jurassic.
The Barremian-aged Wessex Formation of the Isle of Wight, UK, offers a globally significant glimpse into the sauropod dinosaur faunas of the early Cretaceous. These deposits have yielded specimens of several neosauropod lineages, such as rebbachisaurids, titanosauriforms (including some of the earliest titanosaur remains), and possible flagellicaudatans. Here, we report an undescribed sauropod partial hindlimb from the Wessex Formation (NHMUK PV R16500) and analyse its phylogenetic affinities. This hindlimb preserves the left tibia, astragalus and pes, lacking only a few phalanges. NHMUK PV R16500 can be diagnosed based on two autapomorphies: an unusually high distal end to midshaft transverse width ratio in metatarsals III and IV, and the presence of small bump-like projections located in the centre of the proximal articular surfaces of the unguals of pedal digits I and II. The phylogenetic affinities of NHMUK PV R16500 are uncertain: although our analyses recover it as an early-branching somphospondylan, a single character change moves it to close to Flagellicaudata when extended implied weighting is applied. The possibility of flagellicaudatan affinities for NHMUK PV R16500 implies a potential ghost lineage that survived the Jurassic/Cretaceous boundary; however, we present evidence that the somphospondylan position is more probable and should be preferred.
Carcharodontosaurids were gigantic terrestrial dinosaurs and top predators of dinosaur faunas in Gondwanan landmasses during the “Mid”-Cretaceous Period. Despite their wide geographical and stratigraphical distribution, essential parts of their anatomy are still poorly known. The present contribution aims to describe a new partial skeleton of the carcharodontosaurid Taurovenator violantei, which was previously known only by an isolated postorbital bone coming from Cenomanian–Turonian beds of northern Patagonia, Argentina. The neck of Taurovenator is composed of notably high anterior cervicals, bearing neural spines with expanded, flange-like dorsal tips which are successively imbricated. This condition has been reported previously in the carcharodontosaurid Acrocanthosaurus, but its occurrence in Taurovenator and other members of the clade suggests it may represent a synapomorphy of this theropod family. This unique neck morphology was probably related to strong modifications in musculature and restriction in the range of movements within the neck, but not with the head. The new specimen also affords valuable anatomical information on the forelimb of Patagonian carcharodontosaurids. As in other giganotosaurines, Taurovenator shows strongly reduced forelimbs, particularly the forearm, showing hand elements with elongated non-ungual phalanges, and well-marked articular surfaces and muscular insertions, suggesting highly movable digits. This new specimen of Taurovenator allows us to expand anatomical and morpho-functional discussions about the carcharodontosaurid clade.
Stegosaurs are a small but iconic clade of ornithischian dinosaurs. They and their sister taxa, the ankylosaurs, formed the clade Eurypoda which means 'broad-footed'. Here, we describe a stegosaur from the Upper Jurassic Qigu Formation of Xinjiang, China, based on an associated partial skeleton that includes axial, pectoral girdle, pelvic girdle, limb and armor elements. It can be diagnosed as a new taxon, Angustungui , based on numerous autapomorphies. Some morphologies of Angustungui are more similar to the taxa from Europe, Africa and North America than to those from Asia. Our phylogenetic analysis recovers it as the sister taxon of Loricatosaurus . More importantly, the narrow and claw-shaped ungual of Angustungui proves that Eurypoda, at least stegosaur, has claw-shaped unguals. Besides, we revised the character scores for Chinese stegosaurs based on observations of the specimens.
Recent fieldwork in the late Middle Jurassic Balabansai Formation of Kyrgyzstan has yielded a partial skeleton of a large theropod dinosaur. The material includes a few bones of the skull (postorbital, quadratojugal), dorsal and sacral vertebrae, fragments of the pectoral girdle and forelimbs, and an almost complete pelvic girdle and hindlimbs, and is here made the type of a new theropod taxon, Alpkarakush kyrgyzicus gen. et sp. nov. Alpkarakush can be diagnosed by an extremely developed orbital brow on the postorbital, a pneumatic opening leading into cavities in the neural arch from the centroprezygodiapophyseal fossa in the posterior dorsal vertebrae, an almost enclosed ventral sulcus in manual phalanx II-1, a narrow and deep intercondylar groove on the anterior side of the distal femur, and an epicondylar crest on the distal femur that is offset from the distal end. A second, fragmentary, and smaller specimen from the same site represents the same taxon. Based on long bone histology, the type of Alpkarakush represents a late subadult individual, whereas the smaller specimen is a juvenile, possibly indicating gregarious behaviour. Phylogenetic analysis places Alpkarakush in the Metriacanthosauridae, underlining the diversity and wide distribution of this clade in the Jurassic of Asia.
The early evolutionary and biogeographical history of Gondwanan iguanodontian dinosaurs is poorly understood due to their scarce Lower Cretaceous fossil record. In South America, the Lower Cretaceous iguanodontian osteological record is very fragmentary and most published reports cannot be used to discard or confirm hadrosauroid affinities. The single exception is Tietasaura from Brazil, whose incomplete femur shows a combination of traits found only in non-hadrosauroid iguandontians. Furthermore, no skeletal remains whatsoever of Lower Cretaceous iguanodontians have been reported from the western margin of South America. Here, we describe an isolated ornithopod caudal centrum (SGO.PV.22900) from the Lower Cretaceous Quebrada Monardes Formation in the Atacama Desert, northern Chile. Although incomplete, SGO.PV.22900 presents iguanodontian traits, such as the subhexagonal contour of the articular faces, the rectangular profile in lateral view and the absence of transverse processes below the neurocentral suture. We were also able to use quantitative measurements to explore taxonomic affinities, by carrying out a Linear Discriminant Analysis (LDA) and a Principal
Components Analysis (PCA) using measurements of caudal centra of several iguanodontian species. The results of both analyses are consistent with those of our comparisons and suggest that SGO.PV.22900 belongs to a non-hadrosauroid iguanodontian ornithopod. This specimen represents one of the most compelling and best documented pieces of osteological evidence of Lower Cretaceous non-hadrosauroid iguanodontian dinosaurs in South America and provides further support for the presence of iguanodontians in the southwestern margin of Gondwana since at least the Early Cretaceous, as previously suggested based on footprints.
The vertebrate assemblage of the Lower Jurassic Kayenta Formation is known for its preservation of post-end Triassic mass extinction lineages, including lissamphibians, lepidosaurs, turtles, mammaliamorphs, crocodylomorphs, pterosaurs, and ornithischian, theropod, and sauropodomorph dinosaurs. Most of the body fossils from the formation are known from its ‘silty facies’ in north-central Arizona and southwestern Utah, whereas the sandier ‘typical facies’ of northeastern Arizona preserves few body fossils, and until recently they were completely absent in the typical facies of southeastern Utah. A 2011 team conducting a paleontological survey of Arches National Park discovered the first body fossils from the typical facies of the Kayenta Formation in Utah, here identified as belonging to a single individual of a saurischian dinosaur, likely a theropod. The fossil elements include a partial centrum articular face, a prezygapophysis, part of a caudal vertebra, the distal end of a left radius, part of the distal end of a left femur, a shaft fragment from the left fibula, the distal end of right metatarsal I, and the proximal portion of left metatarsals III and IV. This specimen from Arches National Park underscores the importance of federally protected land in fossil resource management and suggests that the typical facies of the Kayenta Formation may be undersampled and could preserve more vertebrate bones than previously thought.
Of the four main Japanese islands, Late Cretaceous dinosaur fossils have been discovered in Hokkaido, Honshu, and Kyushu. Here, we report the first Late Cretaceous dinosaur from the remaining main island Shikoku, an isolated dorsal vertebra from the upper Campanian Hiketa Formation (Izumi Group) in Sanuki, Kagawa Prefecture. The vertebra is incomplete, comprising a robust centrum with a subrectangular profile that is generally characteristic of dinosaurs. Histological examination of the centrum reveals moder- ately packed trabecular bone and the complete absence of pneumatic structures, which precludes referral of the specimen to Saurischia or Pterosauria. Instead, we interpret it as a hadrosauriform ornithischian based on the slightly expanded anterior articular surface of the centrum; heart-shaped outline of the intervertebral surface, resulting from its dorsally wide and ventrally narrow shape; ventral keel; and neural canal partially embed- ded into the centrum. As the ventral positioning of the neural canal is common to Bactrosaurus and higher taxa within Hadrosauriformes, we tentatively refer the specimen to Hadrosauroidea. This discovery provides addi- tional evidence that hadrosauriforms had dispersed into present-day Japan by the Campanian and highlights the potential of the Hiketa Formation to provide additional evidence to improve our understanding of the dino saur diversity at the extreme eastern continental margin of Eurasia.
ABSTRACT—Small-bodied theropod dinosaurs are rare on southern landmasses but have been known from India for a century. Excavations by Charles Matley and rgansankar Bhattacharji in uppermost Cretaceous sediments at Bara Simla, central India in 1917–1919 recovered small theropod vertebral and limb elements originally interpreted as coelurosaurians and separated into at least three species compsosuchus solus, Laevisuchus indicus, Jubbulpuria tenuis) based on features that can now be attributed to their serial position in the vertebral column. The comparatively recent discoveries of Noasaurus leali and Masiakasaurus knopfleri from similar-aged rocks in South America and Madagascar, respectively, and advances in basal theropod systematics led to a revised interpretation of most small-bodied Indian theropods as noasaurid abelisauroids. Here we review and redescribe Laevisuchus, Jubbulpuria, and Compsosuchus, including several elements that until now were thought lost, and describe a new partial noasaurid dentary from central India. The dentary bears the characteristic procumbent dentition of Masiakasaurus, which apparently is absent in Noasaurus. Likewise, cervical vertebrae of Laevisuchus more closely resemble those of Masiakasaurus than those of Noasaurus. Despite these similarities, phylogenetic analyses indicate that the balance of character data supports the Indian noasaurid species outside the sister-taxon pairing of South American and Malagasy species. Bones of small-bodied theropods have been recovered exclusively from the youngest Mesozoic localities in India (e.g., Pisdura, Bara Simla); to date they have not been reported from the slightly older localities in western and central India, from southern Indian sites in the Cauvery Basin, nor from the Vitakri Formation of Pakistan.
A new troodontid dinosaur, Hypnovenator matsubaraetoheorum gen. et sp. nov., is described based on an articulated postcranial skeleton recovered from the fluvial deposits of the Albian Ohyamashimo Formation of the Sasayama Group in Tambasasayama City, Hyogo Prefecture, Japan. Hypnovenator is distinguished from other troodontids by four autapomorphies and a combination of additional features. Our phylogenetic analysis positions Hypnovenator as the oldest and one of the most basal troodontines, forming a clade with Gobivenator mongoliensis. The discovery of Hypnovenator suggests that small-bodied maniraptorans with a sleeping posture were common not only in environments with volcanic and eolian events or alluvial systems but also in fluvial systems. Geometric morphometric analysis of manual ungual phalanges shows that manual ungual phalanges I and III of Hypnovenator exhibit considerable morphological variation but are functionally similar, which differs from those of non-troodontine troodontids, reflecting the transition of manual motion within Troodontinae. Hypnovenator also has mosaic features in the pes related to cursoriality. This study reveals that asymmetrical arctometatarsus occurred by the Albian, and some morphological changes, such as shorter digit IV than digit III and non-ungual phalanges of digits III with roller joints and digit IV with weakly ginglymoid articulation, arose during the early Late Cretaceous.
A new troodontid dinosaur, Hypnovenator sasayamaensis gen. et sp. nov., is described based on an articulated postcranial skeleton recovered from the fluvial deposits of the Albian Ohyamashimo Formation of the Sasayama Group in Tambasasayama City, Hyogo Prefecture, Japan. Hypnovenator is distinguished from other troodontids by four autapomorphies and a combination of additional features. Our phylogenetic analysis positions Hypnovenator as the oldest and one of the most basal troodontines, forming a monophyletic clade with Gobivenator mongoliensis. The discovery of Hypnovenator suggests that small-bodied maniraptorans with a sleeping posture were common not only in environments with volcanic and eolian events or alluvial systems but also in fluvial systems. Geometric morphometric analysis of manual unguals shows that manual unguals I and III of Hypnovenator exhibit considerable morphological variation but are functionally similar, which differs from those of non-troodontine troodontids, reflecting the transition of manual motion within Troodontinae. Hypnovenator also has mosaic features in the pes related to cursoriality. This study reveals that asymmetrical arctometatarsus occurred by the Albian, and some morphological changes, such as shorter digit IV than digit III and non-ungual phalanges of digits III with roller joints and digit IV with weakly ginglymoid articulation, arose during the early Late Cretaceous.
A small-bodied ornithomimosaur, Kinnareemimus khonkaenensis Buffetaut, Suteethorn, and Tong 2009, from the Lower Cretaceous Sao Khua Formation of northeastern Thailand was first reported in 1995, then named in 2009. It is the only report of this group in Southeast Asia and was concluded to be a member of Ornithomimosauria, more derived than Harpymimus and Garudimimus but more basal than Archaeornithomimus. Since then, a few published studies have analyzed the phylogenetic position of Kinnareemimus but failed to find it within the clade Ornithomimosauria. Here, the phylogenetic analyses for assessing the relationships of Kinnareemimus within Ornithomimosauria were performed. The results suggested it might be a basal ornithomimosaur or belongs to the subclade Deinocheiridae. Kinnareemimus shares with deinocheirids the proximally projected cnemial crest and the shape of the fibula in proximal view. Its metatarsal III shows subarctometatarsalian condition with metatarsal III pinched between II and IV but visible in anterior view proximally, which might have evolved independently from other ornithomimids. However, the basal position of Kinnareemimus could also be due to the immaturity and the incomplete nature of this animal.
The Missão Velha Formation (Late Jurassic-Early Cretaceous), often referred to as Brejo Santo Formation, is one of the stratigraphic units of the Araripe Basin, included within the Vale do Cariri Group. This locality, characterised by its fluvio-estuarine paleoenvironment, yielded a diverse paleoichthyofauna while its terrestrial vertebrate record is still poorly known, with a single isolated theropod lateral tooth being briefly cited until now. This study aims to revisit this specimen (UERJ-PMB R008) in order to identify it through the current quantitative and qualitative methods. The quantitative analyses were unable to properly classify the Missão Velha specimen to a single theropod group, indicating paravian, piatnitzkysaurid and abelisaurid affinities, while most of cladistic analyses assigned the UERJ-PMB R008 as an abelisaurid tooth. The specimen was finally assigned as an abelisaurid lateral tooth due to its almost straight distal margin, hooked denticles, similarly sized mesial and distal denticles, a lanceolate cross section and an irregular enamel texture. This assignment represents not only the first definitive theropod record for Missão Velha Formation as it is also the oldest abelisaurid record in the South America, filling part of the 30-million-year gap between Eoabelisaurus and Spectrovenator.
Supposed dinosaur remains were collected between 1859 and 1906 in the Lower Cretaceous Recôncavo Basin (Northeast Brazil). Since these materials remained undescribed, and most were considered lost. Recently, some of these historical specimens were rediscovered in the Natural History Museum of London, providing an opportunity to revisit them after 160 years. The specimens come from five different sites, corresponding to the Massacará (Berriasian-Barremian) and Ilhas (Valanginian-Barremian) groups. Identified bones comprise mainly isolated vertebral centra from ornithopods, sauropods, and theropods. Appendicular remains include a theropod pedal phalanx, humerus, and distal half of a left femur with elasmarian affinities. Despite their fragmentary nature, these specimens represent the earliest dinosaur bones discovered in South America, enhancing our understanding of the Cretaceous dinosaur faunas in Northeast Brazil. The dinosaur assemblage in the Recôncavo Basin resembles coeval units in Northeast Brazil, such as the Rio do Peixe Basin, where ornithopods coexist with sauropods and theropods. This study confirms the presence of ornithischian dinosaurs in Brazil based on osteological evidence, expanding their biogeographic and temporal range before the continental rifting between South America and Africa. Additionally, these findings reinforce the fossiliferous potential of Cretaceous deposits in Bahia State, which have been underexplored since their initial discoveries.
Iguanodontia is a diverse clade of herbivorous ornithischian dinosaurs that were speciose and abundant during the Jurassic and Cretaceous. Although the monophyly of Iguanodontia is well supported, their internal relationships have sparked heated debate due to several phylogenetic paradigm shifts. Late Jurassic basally branching iguanodontians in particular are not well understood in terms of their systematic affinities and evolutionary relevance. Their fossil record in Europe is meager compared with North America, with only a few species currently recognized. Two taxa are currently known from the Upper Jurassic of England, the basally branching styracosternan Cumnoria prestwichii and the putative dryosaurid Callovosaurus leedsi. In the Upper Jurassic of Portugal, the styracosternan Draconyx loureiroi and the dryosaurid Eousdryosaurus nanohallucis are presently the only described basally branching iguanodontians. Here we report a new species of early diverging iguanodontian from the Upper Jurassic Lourinhã Formation of western-central Portugal. The new species is clearly distinguished from all other coeval taxa by an exclusive combination of characters that include a tibia with a cnemial crest that is directed craniolaterally and a fibular condyle that is angled at 90°with respect to the proximal epiphysis, a fibula with symmetrical proximal margins, and a reduced metatarsal I. The phylogenetic relationships of the Lourinhã iguanodontian were explored using maximum parsimony and Bayesian inference. The two analyses recover the Lourinhã iguanodontian as an indeterminate dryomorphan, with more precise affinities precluded due to the current available material. Body size is estimated between 3 and 4 meters for the holotype specimen, adding to the diversity of small ornithopods already recognized in the paleoichnological record of the Lourinhã Formation.
The Kem Kem Group of Southeastern Morocco, North Africa, is well known for theropod remains, especially
isolated teeth. Here, a collection of isolated theropod teeth is assessed for diversity using a combination of linear discriminant,
phylogenetic, and machine learning analyses for the first time. The results confirm earlier studies on Kem Kem theropod
diversity, with teeth referred to Abelisauridae, Spinosaurinae, and Carcharodontosauridae. A single tooth is ascribed to a
non-abelisauroid ceratosaur or a megaraptoran and may represent the enigmatic averostran Deltadromeus. Spinosaurine
teeth are clearly differentiated by all three methodologies, whereas abelisaurid and carcharodontosaurid teeth could only
be distinguished by the machine learning and phylogenetic analyses. This study shows that a combination of independent
methods is most effective at providing strong evidence on theropod dental diversity in a particular assemblage, and that
cladistic and machine learning analyses are the most reliable approaches to identify isolated dinosaur teeth. The
methodology used here is likely to yield results in other dinosaur assemblages where isolated teeth are more abundant
than body fossils.
A new member of Spinosauridae from the Enciso Group (uppermost Barremian–lower Aptian) from Igea (La Rioja, Spain) is here erected on the
basis of axial, pelvic girdle, and hindlimb elements that exhibit a unique combination of characters. Riojavenatrix lacustris gen. et sp. nov. is one of
the latest Iberian and European spinosaurid taxa. It retains a triangular pubic boot, like the megalosaurids, and a medial condyle of the femur that
shows a transitional stage between the anteroposteriorly oriented long axis of non-spinosaurid theropods and the posteromedially oriented long
axis of Spinosauridae. The spinosaurid record of Iberia ranges from the late Hauterivian–early Barremian to the latest Barremian–early Aptian
so far, and both the oldest and the most recent evidence comes from the Cameros Basin, where spinosaurid remains are especially abundant in
the Barremian deposits. A review of the spinosaurid record has allowed us to dismiss the presence of the genus Baryonyx from Iberia; hence, only
Camarillasaurus, Iberospinus, Protathlitis, Riojavenatrix gen. nov., and Vallibonavenatrix are considered to be present in the Early Cretaceous of
Iberia. According to this study, Riojavenatrix is one of the youngest baryonychines in the fossil record.
Large quadrupedal sauropod dinosaurs of the group Titanosauria were globally distributed in the Late Cretaceous. Many
titanosaurian species have been discovered in eastern Asia, but most of them are controversial and represented by poorly
preserved remains. Here, we describe a new titanosaur, Gandititan cavocaudatus gen. et sp. nov., based on a partial
skeleton recovered from the lower Upper Cretaceous of Ganxian County, Ganzhou City, southern China, and comprising
six articulated cervical vertebrae, two partial dorsal vertebrae, and a complete sacrum preserved in articulation with the
first 17 caudal vertebrae and part of the right pelvis. Gandititan can be diagnosed on the basis of the following
autapomorphies: long and narrow fossae present on the dorsal and ventral parts of the lateral surfaces of the cervical
centra, sacral neural spines forming a dorsal platform with wave-shaped lateral margins, anteriormost six caudal
vertebrae with bifurcated neural spines, the presence of prominent triangular flanges on the transverse processes of the
anteriormost caudal vertebrae, a pair of slit-like foramina present on the ventral surface of each anterior caudal centrum,
lateral surfaces of neural arches strongly excavated, additional spinoprezygapophyseal laminae present, and a prominent
lamina extending horizontally between the bases of the pre- and postzygapophyses in some anterior caudal vertebrae.
An expanded phylogenetic analysis places Gandititan as the sister taxon to Abdarainurus, within a clade of nonlithostrotian
titanosaurs that also includes the Chinese titanosaurs Dongyangosaurus, Baotianmansaurus and
Huabeisaurus, as well as the Argentine titanosaur Andesaurus. Such results imply the possible existence of a previously
unrecognized group of titanosaurs in eastern Asia, and potential dispersal of titanosaurs between Asia and South
America during the mid-Cretaceous.
Cretaceous (non-avian) theropod dinosaurs from Australia are poorly understood, primarily because almost all specimens described thus far comprise isolated postcranial elements. In Australia, only three non-dental cranial elements pertaining to Theropoda have been reported: the left and right dentaries of Australovenator wintonensis from the Winton Formation (Cenomanian–lowermost Turonian) of Queensland, and an isolated surangular from the Eumeralla Formation (lower Albian) of Victoria. Herein, we report the first evidence of non-mandibular cranial material of a non-avian theropod from Australia: a left frontal and fused parietal fragment from the Lower Cretaceous (lower Aptian) upper Strzelecki Group of Victoria. The specimen shares several synapomorphies with the frontals assigned to Megaraptoridae, including an anteroposteriorly elongate postorbital articulation and a truncated nasal articular surface. Accordingly, we regard this frontal as Megaraptoridae gen. et sp. indet. We performed both parsimony-based and Bayesian-based phylogenetic analyses to support our assignment, and both analyses support a placement within Megaraptoridae. However, this specimen appears to possess plesiomorphic characters relative to other megaraptorid frontals, lacking dorsoventrally high walls of bone that emarginate the nasal and prefrontal articular surfaces. The plesiomorphies of this specimen have implications for the evolution of the megaraptoran skull roof, suggesting the acquisition of specialised adaptations for longirostry over time. This specimen improves the limited record of Cretaceous Australian theropod cranial remains, and provides limited support for the hypothesis that Megaraptoridae might have originated in Australia.
We describe an isolated, almost complete pedal ungual phalanx from the Middle Jurassic marine carbonate rocks of the Jaisalmer Basin, Rajasthan, north-western India. The ungual bone is triangular shaped, pointed, elongated, asymmetrical, dorsoventrally compressed, ventrally flat, bearing a shallow semi-circular excavation, and almost straight in lateral view. The morphological features, as well as its proportions closely resemble the pedal ungual phalanges of spinosaurid theropods, presently known dominantly from the Cretaceous. The affinity to spinosaurids is supported by bivariate and multivariate analyses. The ungual phalanx is tentatively identified as a basally branching Jurassic spinosaurid under Megalosauroidea. Considering the stratigraphical and geographical provenances, this contribution may represent the oldest record of a spinosaurid.
The broadest diversification of early predatory dinosaurs is represented by the ‘coelophysoid-grade’ neotheropods, but their Hettangian–Sinemurian (ca. 191–201 Ma) record is scarce worldwide. More information is needed to shed light on the evolution of this dinosaur group after the end-Triassic mass extinction (ca. 201 Ma). Here we revisit the anatomy and phylogeny of one of these earliest Jurassic neotheropod specimens, an isolated partial tibia from the lower Sinemurian of the Isle of Skye (Scotland) that was previously identified as probably closely related to Liliensternus liliensterni and coelophysids. However, we found that the Skye specimen is positioned in the branch leading to Averostra (Ceratosauria + Tetanurae), in a polytomy with Sarcosaurus woodi from the late Hettangian–lower Sinemurian of central England and a clade composed of Tachiraptor admirabilis and Averostra. The morphology of the Skye specimen is congruent with that of referred specimens of Sarcosaurus woodi , but because it probably represents a skeletally immature specimen, we assign it to cf. Sarcosaurus woodi . The Skye specimen increases the number of averostran-line neotheropod specimens recorded in the Lower Jurassic of Europe and current evidence indicates that these forms, and not coelophysoids, were relatively common in this part of the world at that time.
Thematic collection: This article is part of the Palaeontology of Scotland collection available at: https://www.lyellcollection.org/topic/collections/palaeontology-of-scotland
Supplementary material: https://doi.org/10.6084/m9.figshare.c.6863016
In 2020, the Australasian palaeontological association Australasian Palaeontologists (AAP) joined the Australian government-supported Australian National Species List (auNSL) initiative to compile the first Australian Fossil National Species List (auFNSL) for the region. The goal is to assemble comprehensive systematic data on all vertebrate, invertebrate and plant fossil taxa described to date, and to present the information both within a continuously updated open-access online framework, and as a series of primary reference articles in AAP’s flagship journal Alcheringa. This paper spearheads these auFNSL Alcheringa publications with an annotated checklist of Australian Mesozoic tetrapods. Complete synonymy, type material, source locality, geological age and bibliographical information are provided for 111 species formally named as of 2022. In addition, chronostratigraphically arranged inventories of all documented Australian Mesozoic tetrapod fossil occurrences are presented with illustrations of significant, exceptionally preserved and/or diagnostic specimens. The most diverse order-level clades include temnospondyl amphibians (34 species), saurischian (13 species) and ornithischian (12 species) dinosaurs (excluding ichnotaxa), and plesiosaurian marine reptiles (11 species). However, numerous other groups collectively span the earliest Triassic (earliest Induan) to Late Cretaceous (late Maastrichtian) and incorporate antecedents of modern Australian lineages, such as chelonioid and chelid turtles and monotreme mammals. Although scarce in comparison to records from other continents, Australia’s Mesozoic tetrapod assemblages are globally important because they constitute higher-palaeolatitude faunas that evince terrestrial and marine ecosystem evolution near the ancient South Pole. The pace of research on these assemblages has also accelerated substantially over the last 20 years, and serves to promote fossil geoheritage as an asset for scientific, cultural and economic development. The auFNSL augments the accessibility and utility of these palaeontological resources and provides a foundation for ongoing exploration into Australia’s unique natural history.
Linkages between hatchling and adult sauropods concerning morphological and ontogenetic growth remain enigmatic, which is even more tenuous in early sauropods. However, discoveries from Southeast Asia could provide significant insights into these questions of developmental history with the recent discovery of a partial juvenile vertebral series from an early sauropod from the early Middle Jurassic Nam Phong Formation, Chaiyaphum province, northeastern Thailand. Here we present the anatomical description of preserved portions of the axial skeleton, including cervical and dorsal vertebrae. Our study demonstrates the presence of 1) incipient laminae and fossae on the centrum; 2) unfused neural arch (cervical and dorsal); and 3) well-marked vertebral lamination system, all of which are osteological hallmarks of an immature growth phase. Particularly, we note that in this hatchling-juvenile specimen, the vertebral lamination complex resembles an adult early sauropod's form, along with no true pleurocoel in the vertebral arches. The co-occurrence of these two characters would strongly indicate a non-eusauropod sauropod affinity. With the presence of the lamination pattern, and the temporal placement of the specimen in the early Middle Jurassic, our material mostly resembles the Tazoudasaurus, so we assign the material to the Vulcanodontidae. Further analysis of this hatchling-juvenile specimen will provide crucial insights into the ontogenetic developmental history and musculoskeletal function, successfully filling a current knowledge gap within early sauropods evolutionary studies.
Theropods originated in the Late Triassic and their relations and early evolution are still topics of discussion. Within Neotheropoda, coelophysoids represent their earliestworldwide radiation and include most Triassic theropods, but their internal relations remain volatile. In this paper, we discuss the significance of a coelophysoid femur from the Rhaetian Tytherington fissures near Bristol, UK. The specimen belongs to a small-sized individual and is complete, but for the fourth trochanter blade. The most distinctive aspects of the femur are a sharply pointed lateral condyle and the pentagonal distal outline. The features that supposedly correlate with ontogenetic development, in addition to several well-developed scars, indicate it probably pertains to a mature individual. Its inclusion in a taxon-character matrix recovered the specimen within Coelophysoidea, but created a polytomy encompassing all members of the group. A definitive referral of the femur to the previously recorded coelophysoid Pendraig milnerae is precluded by the lack of overlap in diagnostic
anatomical parts, the paucity of specimens from the Bristol Channel Triassic fissures, and the possible geological age difference between them.
Previous and new fossils of sauropods are reported from the Papo-Seco Formation (lower Barremian, Lower Cretaceous) at Cabo Espichel, south of Lisbon, Portugal. The fossils were collected from the Boca do Chapim and Praia do Areia do Mastro sites. The sauropods and other vertebrate fossil remains from the Papo-Seco Formation occur in marls, sandstones and some conglomerates in a sedimentary succession interpreted as deposited in lagoonal and estuarine environments, under a tropical climate. The study of the available specimens, including teeth and postcranial remains, suggests the occurrence of Titanosauriform sauropods.
Iguanodontian dinosaurs are known from Middle Jurassic to Late Cretaceous deposits worldwide and are historically important because they include the first fossils to be identified as giant extinct reptiles that later became known as dinosaurs. Due to historical taxonomic practices and the fragmentary nature of many specimens, discoveries from the 19th century were referred to Iguanodon with little appraisal, resulting in the genus becoming something of a ‘wastebasket taxon’. Reinterpretations of holotype specimens are an important step in attempting to understand the evolutionary history of iguanodontian dinosaurs. Here, we redescribe the holotype of Mantellisaurus atherfieldensis, one of the most complete British dinosaur specimens, from the Barremian/Aptian of the Isle of Wight, UK, and assess its phylogenetic position. We find that Mantellisaurus atherfieldensis is a valid taxon distinct from the genus Iguanodon based on three autapomorphies of the premaxilla, maxilla, and scapula, and resolves as an early diverging hadrosauroid styracosternan, representing an important step in the evolutionary history of the ornithopods.
Intensifying macrovertebrate reconnaissance together with refined age-dating of mid-Cretaceous assemblages in recent decades is producing a more nuanced understanding of the impact of the Cretaceous Thermal Maximum on terrestrial ecosystems. Here we report discovery of a new early-diverging ornithopod, Iani smithi gen. et sp. nov., from the Cenomanian-age lower Mussentuchit Member, Cedar Mountain Formation of Utah, USA. The single known specimen of this species (NCSM 29373) includes a well-preserved, disarticulated skull, partial axial column, and portions of the appendicular skeleton. Apomorphic traits are concentrated on the frontal, squamosal, braincase, and premaxilla, including the presence of three premaxillary teeth. Phylogenetic analyses using parsimony and Bayesian inference posit Iani as a North American rhabdodontomorph based on the presence of enlarged, spatulate teeth bearing up to 12 secondary ridges, maxillary teeth lacking a primary ridge, a laterally depressed maxillary process of the jugal, and a posttemporal foramen restricted to the squamosal, among other features. Prior to this discovery, neornithischian paleobiodiversity in the Mussentuchit Member was based primarily on isolated teeth, with only the hadrosauroid Eolambia caroljonesa named from macrovertebrate remains. Documentation of a possible rhabdodontomorph in this assemblage, along with published reports of an as-of-yet undescribed thescelosaurid, and fragmentary remains of ankylosaurians and ceratopsians confirms a minimum of five, cohabiting neornithischian clades in earliest Late Cretaceous terrestrial ecosystems of North America. Due to poor preservation and exploration of Turonian–Santonian assemblages, the timing of rhabdodontomorph extirpation in the Western Interior Basin is, as of yet, unclear. However, Iani documents survival of all three major clades of Early Cretaceous neornithischians (Thescelosauridae, Rhabdodontomorpha, and Ankylopollexia) into the dawn of the Late Cretaceous of North America.
Isolated spinosaurid teeth are relatively well represented in the Lower Cretaceous Wealden Supergroup of southern England, UK. Until recently it was assumed that these teeth were referable to Baryonyx , the type species ( B. walkeri ) and specimen of which is from the Barremian Upper Weald Clay Formation of Surrey. British spinosaurid teeth are known from formations that span much of the c. 25 Ma depositional history of the Wealden Supergroup, and recent works suggest that British spinosaurids were more taxonomically diverse than previously thought. On the basis of both arguments, it is appropriate to doubt the hypothesis that isolated teeth from outside the Upper Weald Clay Formation are referable to Baryonyx . Here, we use phylogenetic, discriminant and cluster analyses to test whether an isolated spinosaurid tooth (HASMG G369a, consisting of a crown and part of the root) from a non-Weald Clay Formation unit can be referred to Baryonyx . HASMG G369a was recovered from an uncertain Lower Cretaceous locality in East Sussex but is probably from a Valanginian exposure of the Hastings Group and among the oldest spinosaurid material known from the UK. Spinosaurid affinities are both quantitatively and qualitatively supported, and HASMG G369a does not associate with Baryonyx in any analysis. This supports recent reinterpretations of the diversity of spinosaurid in the Early Cretaceous of Britain, which appears to have been populated by multiple spinosaurid lineages in a manner comparable to coeval Iberian deposits. This work also reviews the British and global records of early spinosaurids (known mainly from dental specimens), and revisits evidence for post-Cenomanian spinosaurid persistence.
We report the first occurrence in South America of spinosaurid specimens belonging to the clade Baryonychinae. The material comprises three tooth crowns recovered from the Lower Cretaceous (Berriasian–Valanginian) of the Feliz Deserto Formation, State of Sergipe, northeast Brazil. The three specimens have the typical conidont condition, displaying a fluted morphology, veined enamel texture and carinae extending to the cervix region, conditions similar to those shared among spinosaurid theropods. Furthermore, a notable feature is the presence of a serrated carinae composed of 6–7 diminutive denticles per millimetre, a key feature shared by baryonychine spinosaurids. Phylogenetic and multivariate analyses performed on dentition-based and crown-based datasets of theropod taxa confirm the relationship of the three tooth crowns described here with the well-supported spinosaurid clade. Our results retrieve the taxa which comprise the “classically” baryonychine clade as individual branches within a polytomy which includes the three tooth crowns and a subclade of spinosaurines (Spinosaurus + Angaturama/Irritator). Additionally, the discriminant and cluster analyses suggest that the materials are more similar to Suchomimus than to Baryonyx morphometrically, but clearly bearing similarities with baryonychines (sharing a similar morphospace). These new findings paleogeographically expand the occurrence of this clade to western Gondwana, and comprise one of the oldest spinosaurid records worldwide, which brings implications on hypotheses for the emergence and evolution of the clade. Furthermore, these new records indicate the presence of more than one spinosaurid taxon in the Lower Cretaceous deltaic paleoenvironment of the Feliz Deserto Formation.
Current research suggests that the initial radiation of maniraptoran theropods occurred in the Middle Jurassic, although their fossil record is known almost exclusively from the Cretaceous. However, fossils of Jurassic maniraptorans are scarce, usually consisting solely of isolated teeth, and their identifications are often disputed. Here, we apply different machine learning models, in conjunction with morphological comparisons, to a suite of isolated theropod teeth from Bathonian microvertebrate sites in the UK to determine whether any of these can be confidently assigned to Maniraptora. We generated three independent models developed on a training dataset with a wide range of theropod taxa and broad geographical and temporal coverage. Classification of the Middle Jurassic teeth in our sample against these models and comparison of the morphology indicates the presence of at least three distinct dromaeosaur morphotypes, plus a therizinosaur and troodontid in these assemblages. These new referrals significantly extend the ranges of Therizinosauroidea and Troodontidae by some 27 myr. These results indicate that not only were maniraptorans present in the Middle Jurassic, as predicted by previous phylogenetic analyses, but they had already radiated into a diverse fauna that pre-dated the break-up of Pangaea. This study also demonstrates the power of machine learning to provide quantitative assessments of isolated teeth in providing a robust, testable framework for taxonomic identifications, and highlights the importance of assessing and including evidence from microvertebrate sites in faunal and evolutionary analyses.
Hadrosauriformes is a group of ornithopod dinosaurs with a rich and extensive Cretaceous track record. However, their rear foot (pes) anatomy is rather conservative. Thus, distinguishing different putative track producers from morphological differences is often impeded unless their identification is corroborated by stratigraphic and geographic distribution. On the contrary, the forefoot (manus) anatomy of hadrosauriform taxa reflects distinctive characters that, when preserved in tracks, may be critical for identifying their trackmakers. In this study, we examined three manus tracks preserved as sandstone casts, collected from Coniacian deposits of the Frontier Formation, southwestern Montana, USA. Tracks are assigned to Hadrosauriformes according to their steeply inclined morphology, functionally tridactyl condition, presence of hoof-like impressions and crescentic cross-sectional shape. Track preservation suggests that digit II could be extended medially, whereas movements for digits III and IV were limited. The dorsally curved digit II and III impressions indicate that these digits could be hyperextended. One track shows a short, spade-like ungual II impression, suggesting a closer affinity of its producer to hadrosauroid or hadrosaurid ornithopods. Osteological characters of the manus combined with track morphology can help with discerning different hadrosauriform producers, providing important implication for palaeoecological and palaeogeographical reconstructions.
Phu Kao-Phu Phan Kham Mountain ranges, situated on the border of Nong Bua Lamphu, Udon Thani, and Khon Kaen provinces,
northeastern Thailand, bear several localities that yield dinosaurs and other vertebrate faunas in the Lower Cretaceous. However, this area has received relatively little attention from the scientific community and the public. Here we review and report new dinosaur materials recovered from this region, some found decades ago, others discovered recently. We identify and discuss their taxonomy and paleobiodiversity. In the Barremian Sao Khua Formation, theropod dinosaurs were represented by spinosaurids, an early branching megaraptoran, a large indeterminate theropod, and small indeterminate theropods. Sauropods were represented by an indeterminate sauropod, a neosauropod, and titanosauriforms, including probable brachiosaurid and non-titanosaur somphospondylans. Other vertebrate groups, including crocodilians, turtles, fishes, and sharks, indicate a similar composition to other Sao Khua Formation communities in northeastern Thailand. The Sao Khua vertebrate assemblage exhibits the taxonomic diversity of dinosaur fauna and is currently
the best-documented assemblage in the Early Cretaceous of Southeast Asia. The Aptian–Albian Khok Kruat Formation, however, yields less diverse vertebrates. They are represented by freshwater sharks, crocodilians, and spinosaurid theropods. This may be due to sampling bias, environmental, or taphonomic conditions. This study provides the basis for future paleontological exploration and research of Mesozoic vertebrates in northeastern Thailand.
The iguanodontian dinosaurs have a fossil record that extends from the Middle Jurassic to the end of the Cretaceous, by which time they had diversified to become the dominant herbivores of Laurasian ecosystems. They are historically important because fossils of British iguanodontians were among the first to be recognised as the gigantic reptiles that formed the basis for naming Dinosauria. However, the early stages of their evolution remain obscure because of a sparse fossil record, and taxonomic and systematic controversies among non-hadrosaurid iguanodontians abound. In order to shed light on the early stages of iguanodontian evolution, new discoveries and re-interpretations of historic specimens are crucial. Here, we redescribe the Late Jurassic early-branching iguanodontian Cumnoria prestwichii from the Kimmeridge Clay Formation of Oxfordshire, UK, and assess its phylogenetic position. We find that Cumnoria is distinct from the North American taxon Camptosaurus, with which it was previously synonymized, and is valid, possessing two autapomorphies of the pectoral girdle. We recover its phylogenetic position as a non-ankylopollexian iguanodontian. Cumnoria represents one of just four valid ornithopod taxa from the Jurassic of Europe.
The Lo Hueco fossil site (Cuenca, Spain) is one of the most relevant localities for the study of Late Cretaceous continental vertebrate faunas from Europe. The fossil record of theropod dinosaurs from this locality is represented by scarce isolated postcranial materials that were preliminarily attributed to abelisaurids and to a possible giant bird, in addition to a large assemblage of isolated teeth that were related to different maniraptoran clades. Here, we describe an isolated partial left tibia articulated with the proximal tarsals and discuss their taxonomic affinities. A review of the European fossil record of Late Cretaceous theropods was performed to analyze possible changes in the faunistical composition during this period. The specimen from Lo Hueco exhibits some characters that have been interpreted as apomorphies for maniraptoran coelurosaurs and a combination of features compatible with deinonychosaurians. Within this clade, the specimen is more favorably comparable with velociraptorine dromaeosaurids and is tentatively interpreted as a member of this group. This specimen is one of the few non-dental specimens of dromaeosaurids described thus far from the Upper Cretaceous of the Iberian Peninsula and contributes to a better understanding of the composition and evolutionary history of the European theropod fauna during the last stages of the Mesozoic.
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