Abstract Adaptations to diverse substrate environments and tiering behaviours are thought to have contributed to the evolutionary success of echinoids. However, the macroevolution of respiratory structures remains poorly understood because of the fragmentary fossil record. Here, we investigate the evolution of petaloid respiratory structures in Brissopsis , one of the most diverse and specialized genera of deep‐infaunal heart urchins. We describe new fossil specimens of Brissopsis luzonica from Taiwan and the Philippines, dating from the Early Pliocene to the Early Pleistocene, an interval during which fossils of the genus are globally rare. We compiled fossil and extant records of Brissopsis and analysed petal morphology using linear measurements and outline‐based geometric morphometrics. Morphospace analysis shows that petal morphology remained broadly stable through time, with only a slight expansion of morphospace occupation since the Eocene–Oligocene. Petal outline is strongly associated with relative petal size but shows little relationship with body size or pore pair number. Species with convergent posterior petals tend to have relatively smaller petals than divergent forms, suggesting alternative respiratory strategies potentially associated with different environmental conditions and tiering behaviours. Together, these results indicate that much of the petal morphological diversity observed in extant Brissopsis was established early in the evolutionary history of the genus and subsequently maintained throughout the Cenozoic, providing new insights into the evolution of respiratory structures and adaptation in infaunal echinoids.
Abstract This study presents the first comprehensive overview of tiger ( Panthera tigris ) evolution throughout its entire temporal range, from its Early Pleistocene origins ( c . 2.5 Ma) to the present. By integrating morphological, functional and palaeobiogeographical data from across mainland Asia, we identify Panthera palaeosinensis as the most likely ancestral form of P . tigris . The earliest putative record of the latter dates to c . 1.3 Ma, followed by the appearance of archaic subspecies P . t. lui ( c . 1 Ma) and the dwarf form P . t. palaeobeijingensis ( c . 0.75 Ma). Morphological trends indicate progressive adaptations for predation on large prey and rapid killing of medium‐sized prey, coupled with reduced durophagy specializations paralleling those of sabertoothed cats. Body mass reconstructions indicate a general size increase through time, strongly influenced by climate oscillations after the Early–Middle Pleistocene Transition and by the extinction of major competitors. These results provide the first full evolutionary framework for the tiger lineage, highlighting the role of environmental instability in shaping its morphology, size and distribution.
Abstract Baltic amber s.l. , the most abundant amber deposit of insect fossils, is essential for understanding the palaeoenvironment of the Eocene, an epoch characterized by severe climate changes, including the warmest period in the entire Cenozoic. The ecological requirements of the extinct lineages can be deduced from the ecology and distribution of their closest extant relatives, once those have been identified through phylogenetic analysis. Rove beetles (Staphylinidae), the most diverse family of animals and occurring in virtually all terrestrial habitats, are a good candidate for such an endeavour. The subfamily Paederinae is particularly abundant in Baltic amber s.l ., but the majority of these fossils have not been studied. Here, we conduct a comprehensive phylogenetic study of 15 Baltic amber s.l . Paederinae fossil species within a total‐evidence phylogenetic framework that integrates morphology with molecular data from seven gene fragments of extant lineages. We then describe nine of them as extinct species new to science: Homaeotarsus damgaardi sp. nov., Lathrobium arcanum sp. nov., Lathrobium rovnensis sp. nov., Lathrobium athanasii sp. nov., Achenomorphus balticus sp. nov., Nazeris nikitasi sp. nov., Astenus problematicus sp. nov., Sclerochiton hoffeinsorum sp. nov. and Pseudolathra baltica sp. nov. The distribution and bionomics of the extant sister species of all analysed fossil species suggest that the latter were associated with tropical and subtropical climates. We discuss the possible microhabitats present in the Eocene amberiferous forest and scenarios for the biogeographic history of Paederinae in Europe.
Abstract Lepidodendron aculeatum is an arborescent lycopod that populated the vast coal swamps in north‐western and central Europe during the late Carboniferous (Pennsylvanian) from the Bashkirian onwards, dominating the lush vegetation of tropical wetlands. Not only was the species the most prominent producer of the thick coal seams mined in those areas over centuries, these up to 40‐m‐tall plants also represent some of the most iconic fossils of the upper Carboniferous. Lepidodendron aculeatum is known predominantly from trunks and fragments of trunk/branch surfaces, or external moulds, with their characteristic leaf scars (‘scales’), but articulated fossils are very rare. Here, we present a 4‐m‐long, articulated branch system (a partial crown) of Lepidodendron aculeatum , as well as further excellently preserved fossils of trunks/branches with attached leaves, and possible conspecific strobili and sporophylls preserved with particular anatomical details, from the Bashkirian fossil Lagerstätte of Hagen‐Vorhalle in northwestern Germany. Based on the described fossils, we emend the diagnosis of Lepidodendron aculeatum and add information to the common perception of the reconstruction of these iconic arborescent plants.
Abstract Our knowledge of the origin and early evolution of salamanders has benefited greatly from Asian Mesozoic taxa: stem salamanders are known from the Late Triassic to Early Cretaceous of Central and North Asia, and the earliest crown salamanders mainly from the Middle Jurassic to Early Cretaceous of East Asia. No salamanders of Late Cretaceous age have previously been reported from East Asia, hindering our understanding of this crucial time interval when modern salamander families originated. Here we report a new salamander, Changchunerpeton nonganensis gen. et sp. nov., based on computed tomography analyses of an atlantal centrum and four partial long bones from the Upper Cretaceous (Campanian) Nenjiang Formation in Nongan County, Jilin Province, China. The atlantal centrum bears a number of diagnostic features of the primitive salamander family Hynobiidae, including the presence of the spinal nerve foramen, interglenoid tubercle wide and dorsoventrally thin, continuous articular facet on the anterior and lateral faces of interglenoid tubercle, and the spinal cord support extending anterodorsally. This information fills a c . 110 myr gap in the hynobiid fossil record between the Early Cretaceous (Aptian) and Late Miocene (MN9). Evolutionary and developmental patterns of the commonly preserved atlas in fossil lissamphibians are summarized. The interglenoid tubercle has an absent, small to large evolutionary trend in early lissamphibians and its presence is possibly linked to the importance of the centrum in vertebral development. Spinal cord supports in the atlas are found in salamanders and caecilians, and their location and orientation are informative in lissamphibian taxonomy.
