Geobios最新文献

Hydrocarbon seeps represent some of the most extreme marine habitats but are also home to rich communities developed around chemosynthesis rather than photosynthesis. Here we describe the outcrop of Sahune (Drôme department, south-eastern France), that illustrates a new seeping site during the Late Jurassic (middle Oxfordian), as formally demonstrated by geochemical proxies. We report the associated fauna composed of foraminifers, radiolarians, crinoids, echinoids and ostracods that all point to seepage at bathyal depth. The foraminifer assemblage and the occurrence of the irregular echinoid Tithonia oxfordiana together point to a middle Oxfordian age. We provide an in-depth analysis of the ostracod community, which is the oldest so far reported in such environments. The new species Procytherura praecoquum may be cognate to the seepage site and could illustrate the oldest known example of pore clusters, sometimes proposed as representing ectosymbiosis. The Sahune assemblage demonstrates that cold seep ostracod communities were already a mixture of taxa from platform and deep-sea oligotrophic environments. The post-Jurassic diversification of ostracods at cold seeps was related to colonization events and diversification of families that have been inhabitants of such ecosystems at least since the Oxfordian. The Sahune record changes our current conception of the deep-sea colonization by the ostracods Tethysia and Procytherura that occurred earlier than traditionally considered.

We report lignitic fossil rich-beds from the Bathonian Castelbouc sauropod tracksite (Castelbouc Cave N°4, Causses Basin, southern France). Showing the co-occurrence of amber with plant, vertebrate and invertebrate remains, they are a precious tool to reconstruct Middle Jurassic dinosaur ecosystems. A multiproxy approach combining sedimentology, petrology, mineralogy and palaeontology led to determine that these fossil rich-beds were deposited in a range of insular coastal palaeoenvironments. They include protected backshore areas such as freshwater/brackish ponds and brackish bay/lagoon showing co-occurrence of terrestrial and marine inputs. The backshore environments were particularly rich in ostracods (Darwinula sp., Fabanella bathonica) and gyrogonites of charophytes (Porochara douzensis). The abundance of conifer remains including leafy axes (Brachyphyllum), cones (cf. Classostrobus), wood (Brachyoxylon) and pollen grains (Classopollis) shows that ponds and bay/lagoon were bordered by conifer-dominated forests in which Cheirolepidiaceae were the main component. Such a rich and relatively diverse flora was probably an attractive source of food for megaherbivorous dinosaurs. Vertebrate microremains mostly consist of fish scales (Ginglymodi indet.) and crocodylomorph teeth (Atoposauridae indet.), two groups that are common components of Middle Jurassic paralic faunas. The palaeobotanical assemblage suggests a warm subtropical climate probably tropophilous with marked alternation between a wet and a dry season.

Triassic-Jurassic deposits are well developed in Guangdong Province, South China. In particular, the Upper Triassic coal-bearing strata which alternate between marine and terrestrial deposits yield diverse and abundant fossil plants, ammonites and bivalves. These strata provide a significant reference for the study of palaeoenvironmental variations in the lower latitude regions. In this paper, we review the major progress on Late Triassic floral studies in this area. Specifically, we compare the regional plant assemblages from different fossil sites in central and northern Guangdong which have been dated with marine fauna. 155 species belonging to 56 genera of fossil plants have been reported so far in northern and central Guangdong. The Late Triassic floras in Guangdong are mainly composed of Bennettitales and ferns, followed by horsetails, seed ferns, cycads, ginkgos and conifers. In ascending order, four regional plant fossil assemblages can be recognized in the Late Triassic deposits, namely the Pachypteris-Lindleycladus Assemblage (Julian), the Pterophyllum-Baiera Assemblage (late Julian), the Clathropteris-Otozamites Assemblage (Tuvalian), and the Danaeopsis-Anomozamites Assemblage (Rhaetian). In general, the Late Triassic climate in the Guangdong region was mainly humid and warm and either tropical or subtropical. The fossil plants corroborate palaeomagnetic evidence that the central and northern Guangdong region was located at approximately the same latitude as it is today and formed the southern coastline of the South China Block during the Late Triassic. Palaeogeographically, the transgression started at the end of the Julian and the south coastal terrane consisted of a western bay, a peninsula and an eastern bay. During the regression period, post-Rhaetian, the bays evolved into a gulf coastal plain.

Chancelloriids are an enigmatic group of Cambrian animals characterized by radially symmetrical bodies equipped with spiny sclerites. Although they were major components of many benthic communities, current understanding on how this group diversified during the Cambrian remains limited. Clarifying these confusions about the diversification of chancelloriids requires new information provided by new studies of previously described and/or new material. Considering the emerging scenario of chancelloriids, the sack-like chancelloriids from the Stage 4 Balang Lagerstätte are restudied on the basis of previous collections, which are herein separated from Chancelloria eros Walcott, 1920, and revised as Archiasterella acuminata nov. sp. and Chancelloriidae gen. et sp. indet. The Ar. acuminata specimen is well preserved and does show its scleritome and sclerite characters, while the Chancelloriidae gen. et sp. indet. specimen is poorly preserved and its scleritome and sclerite characters are difficult to distinguish. By combining information from previous studies and the present research, data on chancelloriid occurrences in South China indicate that chancelloriids had once diversified in the Cambrian South China, evidenced by high-level richness of sclerite-based taxa during the late Fortunian to the middle Stage 3, and of sclerite formulas during the late Stage 2 to the Wuliuan. The result is inconsistent with the recent viewpoint that there were two flourishing ages of chancelloriids in South China. Although more evidence is needed to support our results, the present study offers insights in understanding the evolutionary dynamics of chancelloriids.

Palaeogiraffa is a poorly understood giraffid genus from the Vallesian of Axios Valley (Northern Greece), Turkish Thrace and Central Turkey. The Axios Valley remains come from three non-contemporaneous Vallesian faunas from the localities: Pentalophos, Ravin de la Pluie, and Xirochori, whereas the Turkish remains come from the Vallesian faunas of Middle Sinap, Yulafli, and Küçükçekmece. Remains from Pentalophos and Ravin de la Pluie were described as congeneric with the Iberian Deccenatherium, although they were later attributed to a new, distinct genus known by three different species: Palaeogiraffa macedoniae, Palaeogiraffa pamiri, and Palaeogiraffa major. The type species of the genus, Pg. macedoniae, was based on the most abundant Pentalophos material, while the rest of the species was established mainly on size difference criteria. Here we provide a review of the Palaeogiraffa material in order to (i) test its validity, (ii) re-discuss hypotheses about the genus phylogenetic relationships with other Late Miocene giraffids, and (iii) re-explore intrageneric diversity and number of recognized species based on the available Eastern Mediterranean samples. We confirm Palaeogiraffa as a distinct genus from other Late Miocene giraffids based on its unique proportions, as well as its dental and postcranial morphology. Furthermore, we endorse the likelihood of Palaeogiraffa being phylogenetically linked to the sivatherine lineage, based mainly on its dental and metatarsal morphological features. The generic attribution of specimens from Xirochori, Ravin de la Pluie, Middle Sinap, Yulafli and Küçükçekmece to Palaeogiraffa is adequately supported by the present data. Nevertheless, the recognition of three species is more open to discussion, though they should be retained until more material is available.

In this paper, we provide the first data on large (cm-sized) coprolites (represented by three morphotypes) comprising a rare occurrence of eight specimens from a total of three vertebrate-bearing horizons identified within the Early Miocene (Aquitanian) Khari Nadi Formation and Middle Miocene (Burdigalian-Langhian) Chassra Formation, Kutch Basin, western India. The geochemical data confirm the phosphatic character of the investigated ichnofossils. The dominance of partly digested bone matter and presence of plant remains in all the three coprolite morphotypes reflects the omnivorous diet of the producers, which were most likely chelonians. The occurrence of an inclusion (in a coprolite specimen recorded in this study) showcasing an ultrastructure similar to mammalian dental enamel is a rarity in Neogene coprolite records. Additional biotic inclusions observed in the investigated coprolites include ostracods (assigned to genera Paractinocythereis, Hermanites, and Propontocypris); large planispiral benthic foraminifera including the genus Quinqueloculina; uniserial and biserial benthic foraminifera belonging to genus Textularia; marine calcareous algae genus Actinoporella; chrysophytes (resting spores or cysts of planktonic algae); sponge spicules (represented by the morphotypes Acanthoxea and Strongyle); freshwater diatom genus Aulacoseira; unidentified fungal remains; and phytoliths. Taken together, the biotic and abiotic (e.g., pyrite) inclusions, geochemical data and associated microbiota suggest that these ichnofossils were deposited in a dominantly coastal marine (intertidal) setting linked to a lacustrine/palustrine environment.

The new Prat de Cest locality (Narbonne-Sigean Basin, Aude, France) provides a rodent fauna composed of Pseudocricetodon thaleri, Simplomys aff. aljaphi, Vasseuromys cf. bergasensis, Plesiosminthus myarion and Rhodanomys occitanensis nov. sp. Eomyidae account for more than 78% of the material collected and reflect a humid and forested environment. The presence of Plesiosminthus myarion and Simplomys aff. aljaphi, the evolutionary stage of Pseudocricetodon thaleri, close to the population of Coderet (MP30) but displaying some derived characters shared by Early Miocene populations, and the intermediate morphology and size of R. occitanensis nov. sp. between Rhodanomys transiens and Rhodanomys schlosseri support a basal MN1 age for Prat de Cest. The glirid Vasseuromys cf. bergasensis is the first occurrence of this genus outside Spain and could also be the first occurrence of Vasseuromys bergasensis in the Early Miocene. The unique faunal association found in Prat de Cest paves the way for a possible subdivision of the MN1 biozone.

This contribution studies some paleobiological aspects of Opisthodactylus kirchneri, a fossil rheid from the Late Miocene of northwestern Argentina. We estimate the body mass of this species using an allometric equation based on long-legged birds. Besides, we estimate the maximum running speed by applying a previously published biomechanical model to study other living and fossil running birds. We perform multivariate analyses with hindlimb measurements used as biomechanical model inputs to compare the fossil rheid with other living ratite species. We found that O. kirchneri would not have been a swift runner as living rheids of South America. We identify the presence of a long distal hindlimb segment correlated with a novel adaptation to paleoenvironmental conditions in southern South America during the Late Miocene. We propose alternative interpretations based on these results and the hindlimb bone proportions.

The giant flightless bird Gastornis laurenti Mourer-Chauviré and Bourdon, 2020, has been described from a mandible, maxilla and quadrate discovered in the early Eocene locality of La Borie (middle Ypresian, reference level MP 8–9). This locality has yielded abundant fossil vertebrates. We describe here new postcranial remains of G. laurenti, a coracoideum assigned to Tegulavis corbalani nov. gen., nov. sp. (cf. Galliformes), a tarsometatarsus attributed to Papulavis annae nov. gen., nov. sp. (cf. Aramidae), and the tibiotarsus of a small gruiform related to either Walbeckornis or Messelornithidae. The study of the postcranial material confirms that the species G. laurenti differs from other species of Gastornis in many features. The avifauna from La Borie is not very diversified but matches well with the paleoenvironment, which consists of an alluvial flood plain with sparse vegetation, in a tropical climate.

LSID of publication: urn: lsid: zoobank.org: pub: 5BA44166-BBEZ-41E7-BG8C-8A1DBCBA14AB.