A fossil spider from the Cretaceous Jinju Formation of Korea is redescribed as Korearachne jinju, n. gen. n. sp. Previous description of this specimen, the only known fossil spider from Korea, was inadequate, and here we present a more detailed interpretation and illustration of the specimen. The fossil spider is preserved alongside juvenile albuiform fish, Diptera and possible crustaceans, which suggests a mass mortality event. Familial identification of the spider is impossible, but it probably belongs to a guild of wandering spiders, possibly lycosoids.

An early Cambrian ichnofauna consisting of Helminthoidichnites tenuis, Helminthopsis tenuis, Multina isp., Oldhamia alata, and Pilichnus cf. dichotomus is documented from shallow-marine deposits ranging from the upper offshore to the offshore transition in the Puncoviscana Formation of northwest Argentina. Although the ichnogenus Oldhamia is more common in Cambrian deep-marine environments, this occurrence provides further evidence that it is also present in shallow-marine environments. The burrow network Multina (senior synonym of Olenichnus) is preserved at the base of tempestites, representing the activity of post-storm colonizers. A drowning surface separating offshore-transition deposits below from upper-offshore deposits above contains widespread evidence of trace fossils in direct association with matgrounds. The undermat miners Oldhamia alata and Pilichnus cf. P. dichotomus occur on this surface, revealing exploitation of organic matter in the biomat. Low sediment rate during drowning and paucity of bioturbation by sediment bulldozers may have promoted the establishment of the matground. In comparison with the simpler animal-matground interactions characteristic of the Ediacaran, the combination of Cambrian evolutionary innovations and the presence of microbial mats promoted more sophisticated interactions. Complex feeding trace fossils revealing that systematic undermat mining, as displayed by Oldamia alata and Pilichnus cf. dichotomus, is a product of the Cambrian explosion.

Tympanal ears in insects are important for both intraspecific communication and for the detection of nocturnal predators. Ears are thought, based on modern forms, to have originated independently multiple times within insects and can be found on multiple regions of the body. Here we describe and document the exceptionally well preserved tympanal ears found in crickets and katydids from the Eocene Green River Formation of Colorado, which are virtually identical to those seen in modern representatives of these groups. These specimens are among the best preserved insect ears in the fossil record and establish the presence of ears in two major clades of Orthoptera 50 million years ago. Also discussed and evaluated are previously described insect ears from the Mesozoic and the implications of the findings of the present study for studying the evolution of ears within insects.

We describe the relatively complete skeleton of Tetraclaenodon undoubtedly associated with its dentition, from the Torrejonian interval of the Nacimiento Formation in the San Juan Basin, New Mexico. Tetraclaenodon is the most primitive and oldest genus of the family Phenacodontidae and is very important for assessing the phylogenetic relationships of the family. The newly described skeleton belonged to a lightly built terrestrial mammal that could use trees for shelter. The structure of the ulna, manus, femur, crus, and pes corresponds to that of a typical terrestrial mammal, while morphological features such as the low greater tubercle of the humerus, long deltopectoral crest, pronounced lateral supracondylar crest, and hemispherical capitulum indicate some scansorial adaptations of Tetraclaenodon. The postcranial skeleton of Tetraclaenodon does not exhibit the cursorial adaptations seen in later phenacodontids and early perissodactyls. Phylogenetic analysis did not recover monophyletic “Phenacodontidae”; instead, phenacodontids formed a series of sister taxa to the Altungulata clade. Tetraclaenodon is the basal-most member of the “Phenacodontidae” Altungulata clade.

We provide the first detailed endocranial description of the petrosal bone of the ear region of the anthracotheriid artiodactyl Bothriogenys, based on two new specimens from the early Oligocene of the Jebel Qatrani Formation, Fayum, Egypt. The new fossils have petrosals with a hyperinflated (pachyostotic) tegmen tympani (the roof over the middle ear), resembling the condition in certain cetancodontans such as hippopotamids and basal cetaceamorphans (fossil stem taxa to extant Cetacea).

The morphology of the petrosal, particularly its relative size and density, has been considered an important indicator of the ability of a marine mammal to localize sound transmitted in water, yet petrosal size (pachyostosis) and density (osteosclerosis) have not previously been quantified independent of each other. We examine the new fossils in the context of a preliminary CT-based study of petrosal density (extant taxa only) and petrosal volume (extant and extinct taxa) in a sample of artiodactyls and outgroups. In our extant comparative sample, the petrosals of cetaceans are both dense and voluminous as has been previously stated. We find, however, that the tegmen tympani is relatively voluminous (pachyostotic) without being particularly dense (osteosclerotic) in Hippopotamus amphibius, an extant taxon that has been documented to show some aquatic hearing behaviors, albeit less derived ones than those seen in cetaceans. A voluminous tegmen tympani, which is present in Bothriogenys, may have specific implications for behavior that are distinct from increases in petrosal density.

The trilobite family Shumardiidae is characterized by small size, lack of eyes, yoked librigenae, and a small number of thoracic segments. Here we report the successive occurrence of three middle Furongian shumardiid species from the Sesong Formation of Korea: Elaphraella? taebaeksanensis n. sp., Elaphraella microforma, and Elaphraella nodus. They appear to represent the oldest shumardiid morphology known so far. This genus lacks the anterolateral swellings on the glabella and has a conical glabella. Its yoked librigenae also encompass a comparatively wide genal field. Elaphraella? taebaeksanensis has a highly inflexed facial suture which may reflect the presence of small palpebral lobes. Taken together, the plesiomorphic morphology of the Shumardiidae can be summarized as having a conical glabella, small palpebral lobes, highly arched anterior cephalic margin, a wide librigenal field, and no anterolateral swellings on the glabella.

A bryozoan fauna containing 11 species is described from the Lower Devonian (middle Lochkovian) of Arroyo del Agua, Sierra de Guadarrama, Guadalajara, Spain. One genus containing one species is new: rhabdomesine cryptostome Fehlerpora insolita n. gen. n. sp. Six additional new species are described: three cystoporates: Cystiramus gracilis n. sp., Fistuliramus guadarramaensis n. sp., and Fistuliphragma tenuis n. sp.; and three trepostomes: Eridotrypella hispanica n. sp., Boardmanella dubia n. sp., and Leptotrypella inesae n. sp. Four further trepostome species were identified: Leioclema incompositum Duncan, 1939, Minussina spinosoformis Astrova, 1964b, Leptotrypella verisimilis Astrova, 1970, and Leptotrypella vulgata Astrova, 1964b. The association is distributed over three different sedimentary environments. The high-energy one representing accumulation of debris from bryozoan-coral-pelmatozoan thickets contains eight species dominated by erect branched forms (six species). Tabulate corals are present, especially branches which most likely belong to Subcladopora? abnormis (Mironova, 1974). The environment with moderate to low wave influence contains only two bryozoan species, one erect branched and one encrusting. The third setting represents bryozoan thickets in situ situated in deeper water, the most tranquil environment characterized by four bryozoan species, dominated by three erect forms. Fenestrate bryozoans are absent from the two higher energy environments, whereas the bryozoan thickets in deeper water contain rare unidentified fragments of fenestrates. The bryozoan fauna shows distinct relations to the Lower Devonian (Lochkovian) of Ukraine, one species is known from the Middle Devonian of U.S.A.

The Paleozoic to Mesozoic grade ‘Protozygoptera’ is revised. It appears to be composed of two main lineages, namely the superfamily Permagrionoidea, and the Archizygoptera. The latter taxon forms a monophyletic group together with Panodonata ( = crown-Odonata plus their closest stem-relatives). Therefore, the ‘Protozygoptera’ as previously understood is paraphyletic. Diagnostic characters of the ‘Protozygoptera’, Permagrionoidea, and Archizygoptera are re-evaluated. The Permolestidae is considered as a junior synonym of the Permagrionidae. The following new taxa are described: Permolestes sheimogorai new species, Permolestes soyanaiensis new species, Epilestes angustapterix new species, Solikamptilon pectinatus new species (all in Permagrionidae); Lodeviidae new family (for Lodevia); Luiseiidae new family (including Luiseia breviata new genus and species); Kennedya azari new species, Kennedya pritykinae new species, Kennedya ivensis new species, Progoneura grimaldii new species (all in Kennedyidae); Engellestes chekardensis new genus and species (in Bakteniidae); and Azaroneura permiana new genus and species (in Voltzialestidae). The Kaltanoneuridae and Oboraneuridae are revised. The evolution of protozygopteran Odonatoptera during the transition from the Permian to the Triassic is discussed. The larger taxa of the permagrionoid lineage apparently did not cross through the Permian–Triassic boundary, unlike the more gracile Archizygoptera. This last group shows a remarkable longevity from the late Carboniferous to the Early Cretaceous. It also presents a great taxonomic and morphological stability, with genera ranging from the Permian to the Triassic, and a wing venation pattern nearly unchanged from the late Carboniferous to the Late Triassic. The mass extinction at the end of the Permian period seemingly had a minor effect on these tiny and delicate insects.

Ichthyosaurs represent one of the most highly specialized lineages of marine reptiles, but our understanding of the evolution of this group is based on specimens found at a surprisingly small number of stratigraphic intervals and localities. The Lower Jurassic (Toarcian) Posidonia Shale of southwestern Germany is one of the richest ichthyosaur-bearing formations in the world and has produced thousands of skeletons, including specimens with preserved soft tissue, and fetal remains inside the body cavity. The most abundant ichthyosaur genus in the Posidonia Shale is Stenopterygius. In spite of almost 200 years of research effort, the number of species in this genus is still a point of active disagreement in the literature. Here, bivariate and multivariate analyses are used to classify both articulated and disarticulated skeletons to the level of species, using measurement data from individual cranial and postcranial elements. Unlike previous classification attempts, this technique pinpoints ontogenetically conserved differences in size and proportion between the species, and so can be applied to adult, subadult, and neonatal specimens. Using this method, three species of Stenopterygius, S. quadriscissus, S. triscissus, and S. uniter are differentiated.

The first skiff beetle fossil and earliest myxophagan, Hydroscapha jeholensis n. sp., is described and illustrated on the basis of a single specimen from the Lower Cretaceous Yixian Formation at Huangbanjigou of Beipiao City, Liaoning Province, Northeastern China. Based on the combination of diagnostic characters of this specimen (e.g., minute and fusiform body, short elytra, tapered abdomen, separated meso- and metacoxae, and 3-segmented tarsi), we suggest that it is a definitive representative of Hydroscaphidae belonging to the widespread hydroscaphid genus Hydroscapha LeConte, 1874. It also represents the only impression fossil of the beetle suborder Myxophaga. This find displays great significance for shedding light on the preservation of the minute aquatic beetles, since it is the first well-preserved impression fossil reported for the suborder, rather than amber inclusion.

Unique among the Rugosa are specialized cyst-like structures in corals from an upper Carboniferous limestone within the Baird Formation in the Klamath Mountains, northern California. These structures, here referred to as septal cysts, occur mostly along the distal margins of the dark line extending along the axes of the major septa as seen in transverse section. However, they also commonly extend beyond the distal extent of those lines and may interrupt the fibrous coating in the more proximal parts of some septa. Their function is uncertain. Also present are small dissepiments which form a ring around the distal margins of the minor septa. These structures, however, do not appear to be related to the development of those septa. Some other taxa, including corals from the Bashkirian of Spain and the Kasimovian of Kansas, possess some specialized structures similar to those in the California specimens suggesting at least a remote relationship.

Recognition of a fossil previously identified as a “large Cretaceous beetle” as a glypheid lobster permits the definition of a new species, Glyphea wiffenae. The specimen was collected from the richly fossiliferous, Upper Cretaceous Maungataniwa Sandstone in eastern North Island, New Zealand. Several other fossil decapods with high southern latitude affinities have been described previously from the unit, supporting the placement of the Zealandia region within the Weddellian Biotic Province. This is only the fourth glypheid known from New Zealand and the first Cretaceous occurrence of the genus in the country.

Members of the Etyidae and Feldmanniidae new family have unique arrangements of the spermatheca and gonopores that permit placement of each in different families and that differentiate each from all other brachyurans. Spermathecal openings are not always positioned along the sternal suture between sternites 7 and 8, suggesting that reproductive architecture within the Brachyura and what was formerly regarded as the Podotremata is considerably more diverse and disparate than previously thought. Etyidae and Feldmanniidae radiated in the early Cretaceous and survived into the Paleogene. New taxa include Steorrosia new genus, Bretonia new genus, Faksecarcinus new genus, and sixteen new combinations.

The fruits of the extinct genus Hemitrapa Miki (Trapaceae) are described from the Miocene Shanwang Formation, representing its first fossil record in the Cenozoic of China. Bearing a fusiform, relatively small fruit body with a very long stalk and four sub-equal, strongly ascending, horn-like arms, the Chinese fossil fruits are described as H. shanwangensis Q. Wang new species. Prior to this discovery, a dispersed, trapaceous pollen Sporotrapoidites erdtmanii (Nagy) Nagy was documented from the same formation. Recent paleobotanical and palynological studies in Europe demonstrated that Hemitrapa was closely related to S. erdtmanii, so the co-occurrence of Hemitrapa fruits and S. erdtmanii pollen at Shanwang implies that they may stem from the same parental plant population. Hemitrapa fruits have been widely recognized from the Miocene of mid-latitudes in France, Austria, the Czech Republic, Kazakhstan, Russia, Korea, Japan and the U.S.A. as well as from the late Oligocene–Miocene of Germany and the late Eocene of the Czech Republic. In contrast, dispersed S. erdtmanii pollen has been recovered from the Miocene in central Europe as well as from the late Eocene to the Pliocene of eastern Asiatic shelf basins near the Bohai Sea, Yellow Sea, East China Sea, and the Sea of Japan. Overall, the microfossil and macrofossil records demonstrate that the parental plants of Hemitrapa might have begun to diversify from the mid-latitudes of Eurasia since the Eocene, flourished in eastern Asia and Central Europe during the Miocene, and become extinct after the Pliocene.

The specimen NHMUK 39514 comprises the cranial remains of a plesiosaur found on the Dorset coast during the middle of the ninetieth century. It was partially described and figured by Owen and variously attributed to Plesiosaurus rostratus (Owen) and to Plesiosaurus conybeari (Sollas). NHMUK 39514 is a partial braincase and mandible. It differs from all other Early Jurassic plesiosaurs known including the two species to which it was originally referred. The mandible presents several pliosauromorph characters but the specimen is identified as Plesiosauria indet. because it has several plesiomorphic characters in its braincase anatomy. This assignment will prevent the introduction of a possible chimera in future phylogenetical analyses and paleobiogeographic reconstructions.

A near complete shell from the Hemphillian 4 (Miocene/Pliocene boundary) Buis Ranch local fauna of Beaver County, Oklahoma, represents a fossil box turtle. An anterior contact of neural III and neural V with costal III and costal V only, respectively, presence of a small contact between the suprapygal and eleventh peripherals, development of a thin peripheral lip for articulation with the posterior plastral lobe, placement of the vertebral III/IV sulcus on neural VII, presence of two anterior musk duct glands, a rounded posterior plastral lobe, an elongate shell outline, and a complete neural series diagnose the fossil as a new species, Terrapene parornata n. sp. A phylogenetic analysis of fossil box turtles places T. parornata along the phylogenetic stem of the extant taxon T. ornata. The holotype of ‘Terrapene longinsulae’ cannot be distinguished from Terrapene ornata and is therefore synonymized. Finally, ‘Terrapene’ corneri lacks characters of crown group Terrapene and may therefore represent a stem box turtle. The provenance of the holotype of ‘Terrapene longinsulae’ is more poorly known than previously recognized and this specimen may originate from Kansas or Nebraska and be early Miocene to late Pleistocene in age. Terrapene parornata is therefore the oldest demonstrable representative of crown group Terrapene (ca. 5.3–4.6 Ma). ‘Terrapene’ corneri from the late Barstovian of Nebraska and fragmentary material from the middle Barstovian of Nebraska by contrast are the oldest representative of the Terrapene lineage (ca. 14.5–11.5 Ma). A review of morphological characters related to shell kinesis reveals that most are highly correlated. The results of the phylogenetic analysis converge upon those of molecular data when these correlated characters are omitted from the analysis.