Subadult Individual Research Articles

A new theropod dinosaur from the Callovian Balabansai Formation of Kyrgyzstan

Abstract 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.

New records of spider flies (Diptera: Acroceridae) in neotropical jumping spiders (Araneae: Salticidae)

Salticidae is the most diverse family within the order Araneae. Acroceridae are obligate parasites of spiders, since they need them to complete their development. The aim of this study is to report for the first time the presence of the species Ogcodes argentinensis Schlinger, 1960 (Diptera: Acroceridae: Ogcodinae) in a sub-adult individual of Jollas leucoproctus (Mello-Leitão, 1944) (Salticidae: Sitticini: Sitticina) and the genus Acrocera Meigen, 1803 (Diptera: Acroceridae) in a sub-adult of Titanattus sciosciae Rubio, Baigorria & Stolar, 2021 (Salticidae: Thiodinini). Both spiders were collected in two different localities from Maldonado department in Uruguay.

The Late Miocene hominoid Ouranopithecus macedoniensis (Bonis, Bouvrain, Geraads & Melentis, 1974): maxillary deciduous dentition and virtual reconstruction of the unerupted permanent teeth

The hominoid Ouranopithecus macedoniensis (Bonis, Bouvrain, Geraads & Melentis, 1974) is known from three Late Miocene localities in Greece. All are correlated with late Vallesian, MN10; more precisely, they are dated between 9.6 and 8.7 Ma. During the last 50 years several fossils of this hominoid have been recovered. The present article describes the first specimen with upper deciduous teeth, recovered from the locality Ravin de la Pluie in Axios Valley (Macedonia, Greece). The upper deciduous dentition of O. macedoniensis is characterised by a small canine relative to the length of the deciduous premolars, with a rounded occlusal crown outline, a trapezoidal dP3 with metacone and a rudimentary hypocone, a sub-squared dP4, and the absence of cingulum. The taxonomic and sexual attribution of the studied material is based on the preserved and virtually reconstructed permanent dentition, using high resolution microcomputed tomography. The morphological and metrical comparisons of the permanent dentition with the available sample of O. macedoniensis, as well as the monospecific character and the strong sexual dimorphism of the Ravin de la Pluie sample, allow its attribution to a female sub-adult individual of this taxon. The upper deciduous teeth of Ouranopithecus macedoniensis preserve some morphological features, that may have a phylogenetic value, but this hypothesis requires further investigation as the available material of all fossil taxa is poor.

New data about the shark fauna of the Brejo Santo formation, Late Jurassic of the Araripe Basin, Northeastern Brazil

The Late Jurassic fauna of the Araripe Basin is represented by chondrichthyans and osteichthyans (Actinopterygii and Sarcopterygii). At the present study, we describe new records of hybodontid shark from the Brejo Santo Formation (Upper Jurassic – Tithonian) and characterize their paleohistology. They are represented by a complete cephalic spine of Planohybodus sp., which indicates sexual dimorphism, being present only in male sharks; as well as by a dorsal spine, which is the most complete found so far for this formation. Microstructural analyzes were performed in the dorsal spine, indicating this specimen as a juvenile, early sub-adult individual, approximately one year old.

The geologically oldest specimen of Pterodactylus: a new exquisitely preserved skeleton from the Upper Jurassic (Kimmeridgian) Plattenkalk deposits of Painten (Bavaria, Germany)

Pterodactylus from the uppermost Jurassic of southern Germany represents one of the most iconic pterosaurs, due to its status of being the first member of the Pterosauria to have been described and named. During the early phase of pterosaur research, Pterodactylus was a wastebasket taxon containing dozens of sometimes distantly related assigned species. Decades later, a comprehensive revision of the genus significantly reduced the number of species. To date, only one species remains in the genus, Pterodactylus antiquus, although the referral of several specimens to this taxon and the taxonomic relationships of them is still debated. Thus far, the genus has been only reported from the Upper Jurassic Plattenkalk deposits of Bavaria, and all of these occurrences are Tithonian in age. Here we describe the first record of Pterodactylus from the Torleite Formation near Painten (Bavaria), which represents the first occurrence of the genus from the Kimmeridgian. The specimen is a complete, articulated and exquisitely preserved skeleton of a small-sized individual. Aside from its old geological age, it is a typical representative of the genus, greatly resembling other specimens from younger strata. Certain characters, such as the overall size, skull length, relative orbit size, and phalangeal formula indicate that the specimen from Painten represents a juvenile to young subadult individual, an ontogenetic stage rarely found among Pterodactylus specimens. The find significantly expands the temporal range of the taxon and represents one of the best-preserved specimens of the genus reported so far.

Elemgasem nubilus: a new brachyrostran abelisaurid (Theropoda, Ceratosauria) from the Portezuelo Formation (Upper Cretaceous) of Patagonia, Argentina

AbstractAbelisaurids are medium–large‐sized theropod dinosaurs that were predominant in the carnivorous fauna during the Late Cretaceous of Gondwana. These predators are abundant in the Cretaceous fossil strata of Patagonia, which yield the best record for this group. In the Late Cretaceous, abelisaurids appear in almost all regions of Gondwana and in all stages, except for the Coniacian, in which they are globally unknown. Here we describe a new abelisaurid,Elemgasem nubilusgen. et sp. nov., from the Portezuelo Formation (Turonian–Coniacian), Patagonia, Argentina. The palaeohistology of the appendicular bones ofElemgasemshows that the holotype was a subadult individual, but had achieved sexual maturity. This taxon is based on several axial and appendicular elements, and is diagnosed by the presence of a marked pattern of rugosity on the lateral surface of the fibula and a dorsoventrally deep lateral wall of the calcaneum. Moreover, the posterior caudal vertebrae have a morphology slightly different from any other abelisaurid.Elemgasem nubilusis recovered as an unstable taxon within Brachyrostra, given that it was recovered as sister taxon of Furileusauria or in several positions within this clade. Despite the problematic phylogenetic relationships ofElemgasem nubilus, it is important because it is the first abelisaurid from the Turonian–Coniacian interval and it increases the diversity of this theropod family at a time of marked turnover in the tetrapod fauna of South America, global climate change, and mass extinction events recorded worldwide in the marine realm.

First Report of the Parasitic Nematode Pseudoterranova spp. Found in Mediterranean Monk Seal (Monachus monachus) in Greece: Conservation Implications

The Mediterranean monk seal (Monachus monachus) is classified as an endangered species by the IUCN, with a global population that does not exceed 800 individuals. There is limited understanding around the biology and health status of the species, rendering possible parasitic infections grave for its conservation efforts. The aim of the current study was the molecular identification of a parasitic nematode found in the digestive system of a sub-adult Mediterranean monk seal individual, that was found stranded in the area of Pagasitikos Gulf, Greece in 2019. Analysis of the stomach contents revealed the presence of two intact female nematode individuals. Standard protocols were followed as DNA extraction of the parasites was conducted and PCR amplification of the cytochrome oxidase subunit I (COI) mitochondrial gene was implemented. Sequencing analysis of a 585 bp-amplified product displayed a 96% similarity of the screened nematodes to the Pseudoterranova bulbosa species. Bayesian inference was implemented for the subsequent tree reconstruction. The phylogenetic tree revealed a clear genetic similarity between our parasitic nematode individuals named as Pseudoterranova spp. and Pseudoterranova bulbosa (bootstrap value: 82%), which is indicated for the first and only time as such, to be found in the waters of the Mediterranean Sea and also in the stomach of a Mediterranean monk seal.

Osteology, paleohistology and phylogenetic relationships of Pellegrinisaurus powelli (Dinosauria: Sauropoda) from the Upper Cretaceous of Argentinean Patagonia

Pellegrinisaurus powelli is a large titanosaurian sauropod from the Upper Cretaceous of northern Patagonia (Río Negro Province, Argentina). The holotype of this species comprises an incomplete femur, four dorsal and 26 caudal vertebrae collected from the Lago Pellegrini locality. A single middle caudal vertebra from the nearby Cinco Saltos locality has been more recently referred to Pellegrinisaurus. With the purpose of increasing our knowledge about the titanosaur faunas of the Upper Cretaceous of Patagonia, here we provide a detailed redescription of the holotype and referred specimens of Pellegrinisaurus, reviewing its diagnosis and phylogenetic position. A histological analysis of the femur of the holotype is also carried out. The diagnostic characters originally proposed for Pellegrinisaurus are here considered invalid because they either correspond with diagenetic deformations of the specimen or are present in other titanosaurs. The new diagnostic features are related with the presence of large lateral blind fossae with distinct dorsal rims in the anterior caudal centra and with a low longitudinal ridge on the posterior side of the femur shaft originated from the trochanteric shelf and extending to the distal third of the shaft. The phylogenetic analysis recovers Pellegrinisaurus as a non-saltasaurid lithostrotian, closely related with Alamosaurus sanjuanensis. The bone histology indicates that the holotype corresponds to a subadult (i.e. sexually mature but still growing) individual. Finally, the caudal vertebra previously attributed to Pellegrinisaurus cannot be referred to this genus and is here assigned to Titanosauria indet.

Taphonomy of a skeleton of Arctocephalus australis (Carnivora: Pinnipeda: Otariidae) from the Holocene of Miramar locality (southern Buenos Aires, Argentina)

The taphonomy of a partial skeleton of the fur seal Arctocephalus australis from the mid-Holocene of Miramar (southern Buenos Aires province, Argentina) comprising most of both hindlimbs and some vertebral elements is herein described and discussed. The main axis of the long bones is oriented perpendicular to the coastline, flexed and slightly disarticulated, while the vertebrae are somewhat arched, possibly suggesting rigor mortis. The specimen was probably transported from a nearby coastal area, and possibly died from starvation with subsequent stranding. Short weathering times, fragmentation and possible rotation of the pelvic region are the main factors affecting the remains. The material corresponds to a subadult individual, determined by the pattern of fusion of the epiphysis and size of long bones. This study adds important information on the taphonomy of Holocene marine mammals and paleoenvironmental conditions influencing the preservation of these pelagic pinnipeds along the Atlantic Ocean compared with the populations of the Pacific Ocean.

First occurrence of musk ox Ovibos moschatus in the Late Pleistocene (MIS 3) record from NW Iberia: Paleobiogeographic and paleoenvironmental implications

A remarkable musk ox (Ovibos moschatus) assemblage was recovered at Cowshead Cave (Picos de Europa Mountains, NW Spain). This find is of special paleobiogeographic relevance since it involves the first occurrence of this species in NW Iberia and extends the boundary of its Eurasian distribution range to the SW.Fossils correspond to at least two individuals: one young male about 20 months old, which includes an extraordinarily well-preserved skull, and one subadult of about 38–44 months. The bone deposit, dated to 34.9 ± 0.4 cal ka BP (MIS 3), accumulated in a karst cave that acted as a natural trap, agreeing with the geomorphology and the good preservation of the remains.Considering that musk ox skulls of young individuals are extremely rare in the Pleistocene record, the detailed comparative study of the skull here presented provides new and relevant information. The skull from Cowshead is larger than modern specimens of similar individual age from Greenland; additionally, some remarkable morphological peculiarities in skull and teeth were identified.One metacarpal of the subadult individual was compared to recent and Pleistocene specimens and was among the largest in the entire sample. Significant differences in morphology and size between fossil and recent metacarpals were detected.Teeth microwear analysis suggests a browsing diet based on twigs and leaves at the time of death, which is consistent with a winter diet.The cold and arid environment inferred from the presence of musk ox is consistent with the paleontological record, since cold-adapted mammals occurred at other contemporary assemblages from NW Iberia.

Palynological analysis of dental calculus from Pleistocene proboscideans of southern Brazil: A new approach for paleodiet and paleoenvironmental reconstructions

The proboscidean Notiomastodon platensis is widely recognized in the Pleistocene of Brazil, but direct evidence for its feeding behavior is scant. In this paper, we report palynological assemblages preserved in dental calculi to infer dietary preferences and habitats. Molar specimens (m1 and M3/m3) with significant calculus accumulation were examined from localities along the Coastal Plain (CPRS) and the Campanha region (western state in Pampa biome) in Rio Grande do Sul state, southern Brazil. Palynomorphs obtained from calculus were identified with light microscopy, and we applied species distribution modelling (SDM) for arboreal/shrub pollen taxa to investigate the environmental contexts for proboscideans during the Last Interglacial (LIG, 120 ka BP) and Last Glacial Maximum (LGM, 21 ka BP). Pollen assemblages indicate a generalist diet for N. platensis, and corroborate previous paleoecological studies. N. platensis from CPRS showed two patterns: the subadult individual was a specialized browser in wooded habitats, inferred from pollen taxa dominated by arboreal species (mainly Myrtaceae), while mature/senile adult individuals were dominantly grazers to mixed-feeders in open habitats inferred from herbaceous pollen (mainly Cyperaceae) mixed with woody elements. For the Campanha region, diet interpretation is difficult due to the absence of pollen; however, Poaceae phytoliths indicate that grasses may have been important food items, notably pooid C3 grasses. N. platensis potentially accessed a more heterogeneous environment with mixed open grasslands and forests around the LIG interval because of the larger extension of forest at the time. Grassland landscapes could have been more foraged by proboscideans around the LGM given the dry and cold climate conditions, which resulted in a northward retraction of forest.

Appendicular skeleton of Protoceratops andrewsi (Dinosauria, Ornithischia): comparative morphology, ontogenetic changes, and the implications for non-ceratopsid ceratopsian locomotion.

Protoceratops andrewsi is a well-known ceratopsian dinosaur from the Djadokhta Formation (Upper Cretaceous, Mongolia). Since the 1920s, numerous skeletons of different ontogenetic stages from hatchlings to adults, including fully articulated specimens, have been discovered, but the postcranial anatomy of Protoceratops has not been studied in detail. A new, mostly articulated subadult individual provides an excellent opportunity for us to comprehensively describe the anatomy of the limb skeleton, to compare to other ceratopsian dinosaurs, and to study the ontogenetic and intraspecific variation in this species. New data provided by the specimen shed light on the lifestyle of P. andrewsi. The young subadult individuals present an array of morphological characters intermediate between the bipedal Psittacosaurus and fully quadrupedal adult P. andrewsi. We compare these observations with a broad range of non-ceratopsid Neoceratopsia (of various locomotor adaptations) and Psittacosauridae (obligate bipeds), which gives us insight into the evolution of the skeletal characters informative for the postural change in ceratopsian dinosaurs.

A new Theriosuchus-like crocodyliform from the Maastrichtian of Romania

We describe a new, small-sized atoposaurid crocodyliform from the Upper Cretaceous (Maastrichtian) of Haţeg Basin, Romania. Aprosuchus ghirai gen. et sp. nov. is represented by a nearly complete three-dimensional skull with articulating mandibles and an associated fragmentary procoelous cervical vertebra that may have belonged to the same subadult individual. The new taxon possesses a heterodont dentition with at least four distinct tooth morphotypes including pseudocaniniform, pseudoziphodont lanceolate, ziphodont lanceolate and ‘low-crowned’ teeth. It differs from Sabresuchus sympiestodon, the other Theriosuchus-like taxon from the same stratigraphic unit, in having less enlarged fang-like teeth, a ‘w’ shaped naso-frontal articulation and extremely large palpebrals strongly fused to the orbital margin. The new taxon shares with other atoposaurids a broad oreinirostral rostrum, a vascular opening on the dorsal surface of postorbital bar, a small antorbital fenestra, a partially septated choanal groove and symmetrically developed lateral compression of maxillary teeth. Other synapomorphies of Aprosuchus are shared by a broader range of taxa including Wannchampsus and paralligatorids. The fossil record indicates that these small, highly specialized crocodylomorphs survived up to the latest Cretaceous by colonizing remote and rather complex insular ecosystems in the western Tethyan archipelago.

The largest flying reptile from the Crato Formation, Lower Cretaceous, Brazil

ABSTRACTThe Early Cretaceous deposits of the Araripe Basin in northeast Brazil has yielded numerous vertebrate fossils, in which pterosaurs are the predominant tetrapods. Almost all specimens of this extinct group of flying reptiles recovered from this basin come from two stratigraphic units, the Crato and Romualdo Formations, with the pterosaurs from the former being usually small to middle-sized and large individuals (with a maximized wingspan over 5 m) being only found in the latter. Here we report on a new specimen (MPSC R 1221) composed of a partial right wing, which is the largest pterosaur discovered from the Crato Formation so far, having an estimated maximized wingspan of 5.5 m. Despite the incompleteness of this material, MPSC R 1221 can be referred to the Anhangueridae based on the length ratio between the metacarpal IV and the first wing phalanx. According to the osteohistological study and the degree of fusion, MPSC R 1221 represents a sub-adult individual, showing that the animal had not reached the maximum size before its death. The present study shows that large-sized pterosaurs were also present in the Crato Formation and that their rarity might be an artefact of preservation.

Osteohistology of the non-mammaliaform traversodontids Protuberum cabralense and Exaeretodon riograndensis from southern Brazil

The current study presents a detailed analysis of the osteohistology of the Triassic non-mammaliaform traversodontid cynodonts Protuberum cabralense and Exaeretodon riograndesis. The data provided here adds new information on the growth patterns of South American traversodontids. A single subadult individual of P. cabralense revealed bone tissues comprising uninterrupted fibrolamellar bone. Patches of slower growing lamellar bone at the periphery of one of the elements suggests a transition to overall slower growth in later ontogeny. The bone tissues of E. riograndensis also exhibit uninterrupted fibrolamellar bone during early ontogeny, but growth became cyclical from mid-ontogeny. The early rapid, sustained growth observed in these taxa is similar to that seen in other traversodontids, and may be related to the achievement of large body size in the derived members of the clade.

Redescription of UALVP 40, an unusual specimen ofChasmosaurusLambe, 1914 (Ceratopsidae: Chasmosaurinae) bearing long postorbital horns, and its implications for ontogeny and alpha taxonomy of the genus

UALVP 40, an articulated and reasonably complete skull of a small chasmosaurine dinosaur collected in 1920 by George F. Sternberg from the lower unit of the Dinosaur Park Formation, Dinosaur Provincial Park, Alberta, Canada, is here redescribed. The focus of the study is on the newly prepared right side of the skull and the hitherto undescribed mandible. There are substantial differences between the right and the left side of the skull, most notably the right postorbital horncore exhibits a greater angle of inclination at 60° from horizontal, which is approximately 15° greater than that of the left. The right side of the skull also shows many unfused cranial sutures that are obliterated on the left side. These unfused sutures and the short predentary lacking an anterior elongation, indicate that UALVP 40 likely represents a subadult individual. UALVP 40 is diagnosed to the genus Chasmosaurus by its possession of the following: (i) premaxillary flange along entire anterior margin of external naris; (ii) supraorbital horns curving posteriorly along their length; and (iii) squamosal dorsal border laterally adjacent to supratemporal fenestra straight in profile, sloping posteroventrally at a shallow angle before ascending farther posteriorly to form lateral border of parietal fenestra. The last character is newly proposed. A bivariate correlation in UALVP 40 and other Canadian specimens of Chasmosaurus bearing long postorbital horncores (>150 mm long) reveals a near isometric relationship between interorbital width and horn length. This may indicate those specimens represent an ontogenetic series of a single species diagnosed by long postorbital horncores.

Crossing the boundary between humans and animals: the extinct foxDusicyon avusfrom a hunter-gatherer mortuary context in Patagonia (Argentina)

The discovery of a grave of the late second millennium BC containing an extinct South American fox,Dusicyon avus, at Loma de los Muertos raises intriguing questions about the relationship between wild canids and humans. This sub-adult individual appears to have been buried in a human mortuary context in a comparable manner to adjacent human burials. It may have been kept as a pet and been considered part of the human social group. The ability of pets, especially canids, to leave the animal world and enter into a special relationship with people may be related to the cosmology of South American hunter-gatherers.

A New Titanosaurian Sauropod from the Hekou Group (Lower Cretaceous) of the Lanzhou-Minhe Basin, Gansu Province, China

Increased excavation of dinosaurs from China over the last two decades has enriched the record of Asian titanosauriform sauropods. However, the relationships of these sauropods remain contentious, and hinges on a few well-preserved taxa, such as Euhelopus zdanskyi. Here we describe a new sauropod, Yongjinglong datangi gen. nov. et sp. nov., from the Lower Cretaceous Hekou Group in the Lanzhou Basin of Gansu Province, northwestern China. Yongjinglong datangi is characterized by the following unique combination of characters, including seven autapomorphies: long-crowned, spoon-shaped premaxillary tooth; axially elongate parapophyses on the cervical vertebra; very deep lateral pneumatic foramina on the lateral surfaces of the cervical and cranial dorsal vertebral centra; low, unbifurcated neural spine fused with the postzygapophyses to form a cranially-pointing, triangular plate in a middle dorsal vertebra; an “XI”-shaped configuration of the laminae on the arches of the middle dorsal vertebrae; a very long scapular blade with straight cranial and caudal edges; and a tall, deep groove on the lateral surface of the distal shaft of the radius. The new specimen shares several features with other sauropods: a pronounced M. triceps longus tubercle on the scapula and ventrolaterally elongated parapophyses in its cervical vertebra as in Euhelopodidae. Based on phylogenetic analyses Yongjinglong datangi is highly derived within Titanosauria, which suggests either a remarkable convergence with more basal titanosauriform sauropods in the Early Cretaceous or a retention of plesiomorphic features that were lost in other titanosaurians. The morphology and remarkable length of the scapulocoracoid reveal an unusual relationship between the shoulder and the middle trunk: the scapulocoracoid spans over half of the length of the trunk. The medial, notch-shaped coracoid foramen and the partially fused scapulocoracoid synostosis suggest that the specimen is a subadult individual. This specimen sheds new light on the diversity of Early Cretaceous Titanosauriformes in China.

An articulated hindlimb of a basal iguanodont (Dinosauria, Ornithopoda) from the Early Cretaceous Las Hoyas Lagerstätte (Spain)

AbstractAn isolated, fully articulated hindlimb of a basal iguanodont from the Spanish Las Hoyas Lagerstätte is described. It probably belonged to a juvenile or subadult individual. Despite some slight differences, anatomical features, as well as the late Barremian age of this specimen, would suggest that it belongs toMantellisaurus atherfieldensis. The exquisite preservation of this specimen provides information on the foot anatomy of basal iguanodonts. This is the first report of a non-theropod dinosaur from Las Hoyas. From a palaeoecological point of view, this discovery indicates that potential prey of the carcharodontosaurian theropodConcavenatorwere present at Las Hoyas, thus complementing our knowledge of the trophic structure of this Early Cretaceous palaeocommunity.

A New Titanosaur Sauropod Dinosaur from the Upper Cretaceous of North Patagonia, Argentina

A new sauropod titanosaur from the Upper Cretaceous Anacleto Formation is described. Narambuenatitan palomoi gen. et sp. nov., is diagnosed by cranial and axial autapomorphies. The holotype, which represent a subadult individual, consists of the left premaxilla and maxilla, braincase, both quadrates, one cervical vertebrae, one dorsal vertebra, fragments of cervical and dorsal ribs, seventeen caudal vertebrae, caudal transverse processes, fragments of haemal arches, left sternal plate, right coracoid, left humerus, left ulnae, both pubes, iliac pedicel, proximal fragment of right ischia, and an incomplete left femur. The phylogenetic analysis indicates that Narambuenatitan is a non-eutitanosaurian lithostrotian, and that it shares with Epachthosaurus a neural spine in middle caudal vertebrae which are laminar and posteriorly elongated.