Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The Middle Devonian (Givetian) Valentia Slate Formation in the Iveragh Peninsula, southwest Ireland, is more renowned for the second oldest record of tetrapod trackways in the world than for its heavily metamorphosed bone remains. The present study focuses on new discoveries of non-tetrapod sarcopterygian fish fossils from the Valentia Slate Formation. Micro-CT scanning technology allows a re-interpretation of a previously published acanthodian fin spine as a fanged coronoid of a probable Rhizodontida and the identification of a Dipnoi tooth plate and bone. In addition, a scale of Holoptychius is described. The presence the rhizodont suggests Gondwanan ties and a first northward dispersal wave of these vertebrates into Euramerica as early as middle Givetian. This hypothesis is supported by the common occurrence of the placoderm Bothriolepis in the Valentia Slate Formation.

The Lower Cretaceous fossil site of Las Hoyas (Cuenca, Spain) has yielded the richest Cretaceous avifauna of the European continent. We describe a new fossil (MUPA-LH-33333) of an enantiornithine bird from this locality. This specimen consists of a partially articulated skeleton preserving portions of the vertebral column, both girdles and limbs, ribs and sternum; it also preserves patches of soft tissues including remigial feathers and integumentary structures belonging to the postpatagium. MUPA-LH-33333 shares dimensions and some anatomical features with the holotype of Concornis lacustris, a species previously described from Las Hoyas. However, the new specimen shows differences especially in the coracoid and the sternum, suggesting the presence of a different morphotype closely related to C. lacustris. Nevertheless, the poor preservation prevents asserting that it represents a new species. Histological evidence from its long bones indicates that is subadult or adult and that early fast rates followed by slower and protracted cyclical phases took place during its growth, a previously unnoticed pattern in Lower Cretaceous enantiornithines. This new finding supports the hypothesis that enantiornithines regularly inhabited the Las Hoyas wetland, making this site a hotspot for enhancing our understanding of the evolution and life history of these Cretaceous birds.

The Early Devonian (Emsian) vertebrate fauna of the Gaspé Peninsula, Quebec (Canada) shows close affinity with the Emsian fauna from the Atholville beds, New Brunswick (Canada). Specimens collected in the early 2000s from several localities in central Gaspé include molds of tooth whorls and isolated teeth that we assign to the stem chondrichthyan Doliodus. Isolated teeth of this taxon were first described from the Atholville beds in the late 1800s by Arthur Smith Woodward, who erected a new species Diplodus problematicus. Whereas the Atholville beds teeth are usually preserved individually or in tooth families, and as hard tissue, the Gaspé teeth are mostly preserved as molds of tooth whorls, with individual teeth sharing a thin bone base. Thin sections of Doliodus teeth from the Atholville beds show parallel close-set vascular canals extending above the base plate and through tooth bases, with teeth formed of osteodentine and meso- or orthodentine. We consider that all the known dental elements assigned to Doliodus are conspecific with the articulated Doliodus specimen and thus all are assigned to the same species D. latispinosus. The teeth are compared with the diplodont teeth of other stem chondrichthyan taxa, in particular the Omalodontiformes.

Squaloraja is a genus of chimaeriform fishes known from the Early Jurassic. It has a dorsoventrally flattened body and a long median rostral cartilage. Males have a lance-like tenaculum that articulates with a central groove on the dorsal face of the median rostral cartilage. The genus is the only member of the family Squalorajidae, itself the only family in the suborder Squalorajoidei of the order Chimaeriformes. Phylogenetic analyses suggest a divergence of the Squalorajoidei from other Chimaeriformes in the Mississippian, implying the existence of a ghost lineage of more than 130 My. A spine that resembles a median rostral cartilage of a male Squaloraja was found in the St. Louis Formation (Visean) of Indiana, USA. As in Squaloraja, the dorsal face has a long narrow groove that would have articulated with a long narrow tenaculum. The spine is designated as the holotype of Sulcacanthus schachti, n. gen. et sp. Sulcacanthus is tentatively assigned to the Squalorajoidei based on morphology, but the possibility of convergence cannot be eliminated. A holocephalan tenaculum from the same locality might belong to the same taxon as the median rostral cartilage but could also belong to the suborder Myriacanthoidei.

When first described based on isolated scales, Ligulalepis was assigned to thePalaeoniscoidea, a basal group of actinopterygians (ray-finned fishes). Recent cladisticanalyses, mainly based on skull and neurocranial characters, have mostly recovered thetaxon (or, ‘Ligulalepis’) as a stem osteichthyan. Here we present information on Ligulalepisdermal elements other than scales and skulls, that include a cheek fragment, a premaxilla,other marginal jaw elements and teeth, an accessory vomer, a partial shoulder girdle,incomplete spine-like elements, and a gular plate. The shoulder girdle and premaxilla compareclosely with those of basal actinopterygians, whereas the spine-like element showssome similarity to the distal end of the spines on medial dorsal plates of the Chinese LateSilurian stem osteichthyans Guiyu and Sparalepis, or alternatively to fin rays on the stemosteichthyan Dialipina. One of the jaw elements appears to be a compound jugal plate pluspart of the dentate maxilla, an arrangement not previously known in any Devonian stemosteichthyan, or actinopterygian. Histological structure of dermal plates somewhat resemblesthat of Meemannia, but pore openings in Ligulalepis lead only to the vascular canalnetwork at the base of the ornament layer and not to a pore canal network. Like previousphylogenetic analyses, our analysis incorporating post-cranial dermal skeleton charactersalso recovered Ligulalepis as a stem osteichthyan.

The external and internal features and the microstructure of the asymmetric rhynchonellides from the Albian–Cenomanian (Cretaceous) transition from the Alicante Province (Eastern Prebetic, Southeastern Spain) have been herein studied. Previous authors placed these rhynchonellides in Cyclothyris difformis, consequently attributing an unquestionable Cenomanian age (Upper Cretaceous) to the deposits in which they appear. The long dorsally concave crura and the leptinoid pattern microstructure of the shell confirm their attribution to the genus Cyclothyris. However, among other diagnostic criteria (e.g., ribbing pattern, relative width), C. difformis shows facultative type of asymmetry; while the forms studied here show obligate asymmetry. Therefore, the new species Cyclothyris ementitum sp. nov. is formally described, being characterized by the biconvexity of its shell, its obligate type of asymmetry and an ornamentation of around 25 ribs on each valve. Thus, the study and revision of these rhynchonellides has contributed to updating the record and distribution of the asymmetric Cretaceous rhynchonellides of the genus Cyclothyris. This work opens a new line of research to better understand the biostratigraphical calibration of the Cretaceous sediments from the Eastern Prebetic, and a new insight into the possible origin of the obligate asymmetry present in C. ementitum.

The Cueva del Hueso is located in Castrillón, Asturias. In this work, we carried out a taxonomic, palaeoecological and biochronological study of the micromammals that inhabited the cave environment during the genesis of its most recent level, Level 0. The recovered assemblage presents considerable diversity, yielding a minimum of 286 individuals belonging to 16 taxa. This species association indicates that the landscape would be dominated by open areas and forested patches, with cooler climatic conditions than the current. The presence of Rattus sp. and Mus musculus, along with the climatic inferences, have allowed estimating a relative chronology for Level 0 between 450 AD and 1850 AD.

The early chondrichthyan order Omalodontiformes from the late Early Devonian through to the Late Devonian is characterised by specific teeth. Unlike in most Devonian sharks, their bases are directed labially or are reduced and devoid of labial or lingual extensions. In this paper the complex history of investigation on the dermal skeleton of omalodontiforms is presented and the validity of the established taxa is revised. The dentition of an Emsian representative of this group, known from a single articulated specimen (NMBG 10127) and several isolated fin spines from Canada and previously, probably incorrectly, attributed to Doliodus, is distinctly heterodont. The nature of this heterodonty suggests that the two omalodontiform tooth-based genera described originally from the Middle/Upper Devonian Aztec Siltstone (Antarctica), viz. Portalodus and Anareodus, are in fact congeneric as their teeth represent different parts of the same jaw. Because the teeth of the Canadian specimen differ in important aspects from those of typical Doliodus and are generally similar to those of Portalodus, it probably should be placed in a new genus. Also, the validity of the distinction between Portalodus bradshawae and P. mannoliniae is considered questionable.

Scales of a new thelodont species, Amaltheolepis terranovi sp. nov., are described from the upper Emsian, Lower Devonian Shevchenkinskaya Formation of Novaya Zemlya, Arctic Russia. The new species shows strong resemblance with the Emsian “Verdalen assemblage” from Spitsbergen, supporting an Emsian age for the upper part of the Shevchenkinskaya Formation. This conclusion in the context of the various Amaltheolepisassemblages from Spitsbergen allows for a more accurate comparison and correlation between assemblages from different regions in the Northern Hemisphere, suggesting that the type species, Amaltheolepis winsnesifrom Spitsbergen, is Eifelian in age