Geobios最新文献

A proposed new Ordovician asterozoan genus and species, Cantabrigiaster fezouataensis, has been recently described and assigned to the class Somasteroidea. An accompanying phylogenetic analysis treated twenty-two asterozoans and sixteen early non-asterozoans, one of the latter providing the outgroup. The phylogenetic hypothesis focused on derivation of the subphylum Asterozoa and emphasized the Crinoidea; Cantabrigiaster fezouataensis was interpreted as documenting a critical transition stage in the origin of the Asterozoa. The diagnosis for the proposed new generic name posits absence of ambital framework ossicles as the single character expression that distinguishes Cantabrigiaster among somasteroid genera. Ambital framework ossicular presence is documented here in the holotype and other members of type suite; Cantabrigiaster is synonymized with Villebrunaster Spencer and V. fezouataensis nov. comb. is redescribed. The data matrix for the former Cantabrigiaster phylogenetic analysis relies on an earlier study treating overall echinoderm construction. Expressions outlined in the earlier study are not amenable to transfer to a data matrix without evaluation of level of universality of each cited expression; such evaluations were not provided thereby leading to flawed phylogenetic conclusions that are rejected. An alternative hypothesis for the early history of the Asterozoa supported by aspects of the fossil record, that subphylum diversification preceded the origin of readily preserved skeletons, and therefore potentially no tenable pre-asterozoan outgroup candidate survives in the fossil record, has not been falsified.

Pecopteris (Brongniart) Sternberg is a morphological fossil genus with a cosmopolitan distribution during the Permo–Carboniferous, of which most species belong to the marattialean and or “filicalean” ferns or less frequently to pteridosperms. The taxonomic affinity is uncertain unless distinctive reproductive organs or rachis anatomy is known. Among the numerous species of Pecopteris in the Permian Wuda Tuff Flora, Inner Mongolia, China, Pecopteris lativenosa Halle has been considered as a pteridosperm based on its larger variation of frond morphology, although evidence of fertile organs or rachises are unknown. Newly discovered specimens of this species from the Wuda Tuff Flora are mostly impression fossils. However, some have partially permineralized petioles and have fronds in organic connection to Caulopteris-type stem. Fronds are tripinnate; penultimate pinnae lengths are variable as are ultimate pinnae lengths. Pinnules are oval and thick, and their midveins are straight and are of stable thickness. Lateral veins are dense, bifurcating 1–3 times. Petiole and rachises are anatomically preserved and show sclerenchyma, fundamental tissue and vascular tissue. Vascular bundles of petioles and rachises are C-shaped with two laterally inrolled ends, which are typically stewartiopterid petiole/rachis of Marattiales. These features allow us to assign Pecopteris lativenosa to the late Paleozoic marattialean family Psaroniaceae.

This paper analyzes the first systematic faunal record of the 1755 Lisbon tsunami in the Mediterranean. On the basis of sedimentological and paleontological features, the sedimentary record of a core collected in Gibraltar was divided into six sedimentary facies, with a paleoenvironmental evolution from a shallow marine paleoenviroment to an increasingly restricted lagoon. This record includes a bioclastic layer deposited by the 1755 Lisbon tsunami and characterized by an erosive base, presence of basal rip-up clasts and abundant shell debris composed by marine and brackish molluscs. The paleoenvironmental reconstruction derived from the foraminiferal analysis is congruent with that inferred from the sedimentary and the macrofaunal reconstructions, with the introduction of brackish species into the innermost, intertidal areas of a confined lagoon. This paleontological record is the first faunal evidence of the 1755 Lisbon tsunami in the Mediterranean.

A new echinoid belonging to the genus Habanaster is described from the Western Pyrenees (Pamplona basin, Spain). Definition of Habanaster itzae nov. sp. is based on 16 well-preserved specimens that were collected from Lutetian levels (middle Eocene) of the Anotz Formation. These levels have been interpreted as deposited in low energy, hemipelagic conditions. Habanaster itzae nov. sp. is older than the single formerly known Caribbean species H. sanchezi that occurs in Priabonian (late Eocene) levels from the Consuelo and Jabaco formations. A phylogenetic analysis places Habanaster among the Ovulasteridae. The family is part of a clade, including also the Aeropsidae, that gathers micrasterid spatangoids adapted to offshore or bathyal muddy environments.

Some researchers using traditional taphonomic criteria (groove shape and presence/absence of microstriations) have cast some doubts about the potential equifinality presented by crocodile tooth marks and stone tool butchery cut marks. Other researchers have argued that multivariate methods can efficiently separate both types of marks. Differentiating both taphonomic agents is crucial for determining the earliest evidence of carcass processing by hominins. Here, we use an updated machine learning approach (discarding artificially bootstrapping the original imbalanced samples) to show that microscopic features shaped as categorical variables, corresponding to intrinsic properties of mark structure, can accurately discriminate both types of bone modifications. We also implement new deep-learning methods that objectively achieve the highest accuracy in differentiating cut marks from crocodile tooth scores (99% of testing sets). The present study shows that there are precise ways of differentiating both taphonomic agents, and this invites taphonomists to apply them to controversial paleontological and archaeological specimens.

Biomechanical analyses provide unique insights on state shifts in the ecology of extinct communities. Ammonoids present a compelling case study for coupling biomechanical analysis with ecology given their robust fossil record of external conchs. We present a trajectory model to evaluate hydrodynamical advantages and challenges associated with ammonoid conch form. The model is a one-dimensional calculation estimating the dynamic feedbacks between different components of an ammonite’s motion including thrust, drag, acceleration, and distance traveled. Computational fluid dynamics simulations were performed on eleven different ammonoid conch morphotypes and integrated into a mathematical model to analyze the dynamics of swimming across a combination of conch diameters (5, 10, and 20 cm) and jet rhythms (a single jet or series of three pulses). We compared the efficacy of short-term bursts of motion to that of long-term cruising and found: inflated shapes (i.e., spherocones) offer the fastest short-term motion, but at the greatest costs; heavily streamlined shapes (i.e., platycones) offer long cruise distances, but with ineffective short-term motion; and visibly-coiled shapes (i.e., serpenticones) appear to offer intermediate performance in both locomotion styles. Size is critical in ranking the performance of different conch shapes in both locomotion styles because ranking is determined predominantly by the amount of thrust an animal is capable of generating. With increasing size, Reynolds number increases and the effects of second-order morphological characters become more pronounced and alter the performance ranking of conchs. Finally, we present a visual analysis of the flow regimes and shape details that may drive these hydrodynamic consequences. We speculate that serpenticone morphologies capitalized on these subtleties with a morphology that provided reasonably high-speed swimming at small sizes relevant to juveniles while maintaining relatively efficient coasting locomotion at the larger sizes relevant to adult animals. We highlight the ubiquitous serpenticones of the Early Jurassic as a case study for applying biomechanical data to a paleoecological context. The broad range of morphotypes expressed by ammonoids in the Late Triassic is dramatically pared down during the End Triassic extinction. In the few million years following the extinction, ammonoids diversify into a suite of shapes with a more restricted range of locomotor performance, and only much later is the full range of morphology recovered.

An almost complete and partially articulated skeleton of an Early Pleistocene baleen whale is here described. The fossil, measuring 11 m in length, was discovered in the Calcarenite di Gravina Formation at Lama Lamasinata site (Bari, southern Italy) in 1968. The bifurcated first rib combined with other characters supports the identification of the fossil whale as a possible undescribed species of Balaenoptera (Mysticeti, Balaenopteridae), close to or nested in the B. borealis–B. edeni–B. ricei clade. However, the limited number of preserved diagnostic characters suggests a prudent assignment of the Bari whale to Balaenoptera sp. The associated molluscs suggest a mid-shelf setting deposition near to the boundary between infralittoral and circalittoral environments, probably 40–60 m deep. An associated Carcharodon carcharias tooth (the first case of a possible trophic interaction between white shark and cetaceans in the Pleistocene) and shark bite marks on a rib support the hypothesis that an early scavenger action prevented the rising of the whale carcass because of the removal of abdominal tissues and the consequent reduction of the decomposition gas accumulation. The occurrence of chemosymbiotic bivalves near the skeleton could testify the development of the sulphophilic stage during decay. Overall, the Bari whale skeleton and its associated fossil fauna represent the first well-documented case of Pleistocene whale fall community. The Bari specimen sheds new light on the diversity and disparity of the mysticete fauna in the Mediterranean Pleistocene also related to the geodynamic, palaeoclimatic and palaeoceanographic conditions that favoured upwelling events and nutrients supply into the southern Adriatic basin.

The genus Danaeopsis Heer ex Schimper is a typical and widespread Triassic eusporangiate fern and is also an important species in China with abundant records. In this study, a further investigation of Danaeopsis fecunda is achieved based on additional specimens from Yunnan Province, China. New features for the leaf morphology and pinnae arrangement of D. fecunda have been extended. The fossil record in China suggest that D. fecunda is a key species in the Northern Floristic Region (NFR) of China, spreading from the NFR to the Southern Floristic Region via the transitional zone in the Carnian and distributing in Yunnan in the Norian. In addition, the global tempo-spatial distribution pattern and the palaeoclimate implications of Danaeopsis are discussed. The genus Danaeopsis was distributed in Europe, Asia and even in Australia with warmer and humid, rarely semi-arid conditions in the Triassic. The wide-ranging distribution of Danaeopsis could be largely related to the palaeoclimatic pattern in the Triassic.

The Suidae from the late Miocene of Alsótelekes (northeastern Hungary, Borsod-Abaúj-Zemplén county) are described and assigned to Propotamochoerus palaeochoerus (Suinae) and cf. Parachleuastochoerus (Tetraconodontinae). The co-occurrence of these two taxa agrees with a reference to the early Vallesian (MN 9), as previously indicated from biochronological correlation of the small mammal fauna, and suggests the presence of woodland environments, with abundance of below-ground resources and direct access to water. This fits well with the diverse wetlands and riparian forests that characterized Lake Pannon ∼10 Ma, as documented in the geographically close site of Rudabánya. The convoluted taxonomy of European Tetraconodontinae is discussed.