A new species of Oikozetetes, O. mounti n. sp. is described from the upper Mernmerna Formation (equivalent to Cambrian Series 2) in the eastern Flinders Ranges, South Australia. Description of both shell morphotypes (morph A and B) from the same stratigraphic horizon favors the interpretation of a two-shelled scleritome for Oikozetetes. Identification of at least two types of halkieriid sclerite (palmates and siculates) in stratigraphic association with the Halkieria-like shells of Oikozetetes suggests that these elements are derived from the same scleritome. This provides evidence against previous suggestions that the Gondwanan species was aspiculate; the scleritome arrangement is interpreted to be similar to Halkieria evangelista Conway Morris and Peel, 1995 and supports placement in the family Halkieriidae Poulsen, 1967. Comparison of modes of accretionary growth in Oikozetetes shell morphotypes to Halkieria shells and terminal plates in modern polyplacophorans, supports a scleritome model that places shell morphs A and B in posterior and anterior locations, respectively, along the axis of the body.

The horseshoe crab Limulus polyphemus (Linnaeus, 1758) is a famous species, renowned as a ‘living fossil’ (Owen, 1873; Barthel, 1974; Kin and Błażejowski, 2014) for its apparently little-changed morphology for many millions of years. The genus Limulus Müller, 1785 was used by Leach (1819, p. 536) as the basis of a new family Limulidae and synonymized it with Polyphemus Lamarck, 1801 (Lamarck's proposed but later unaccepted replacement for Limulus, as discussed by Van der Hoeven, 1838, p. 8) and Xyphotheca Gronovius, 1764 (later changed to Xiphosura Gronovius, 1764, another junior synonym of Limulus). He also included the valid modern genus Tachypleus Leach, 1819 in the family. The primary authority of Leach (1819) is widely recognized in the neontological literature (e.g., Dunlop et al., 2012; Smith et al., 2017). It is also the authority recognized in the World Register of Marine Species (WoRMS Editorial Board, 2021).

We report charadriiform and charadriiform-like birds from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). A partial skeleton of a small modern-type charadriiform is described as a new species, Charadriisimilis essexensis n. gen. n. sp., and most closely resembles taxa of the Charadrii (plovers, stilts, oystercatchers, and other “wader-like” shorebirds). Affinities to this clade were also supported by phylogenetic analyses, which placed the fossil as the sister taxon of either the Burhinidae or all crown group Charadrii. In addition, we identify specimens of the charadriiform-like taxon Scandiavis, which was before known only from the early Eocene Fur Formation in Denmark. Associated limb elements of two individuals are classified as Scandiavis cf. mikkelseni Bertelli et al., 2013, and remains of two further individuals are tentatively assigned to Scandiavis. The presence of a processus supracondylaris dorsalis on the previously unknown humerus corroborates charadriiform affinities of Scandiavis, whereas a plesiomorphic hypotarsus morphology indicates a position outside crown group Charadriiformes. Charadriisimilis essexensis is one of the earliest modern-type charadriiforms, and the holotype of the species is the most substantial early Paleogene fossil record of a charadriiform bird. Together with Scandiavis, as the best-represented taxon to be considered as a stem group charadriiform, it provides the basis for an improved understanding of the evolutionary history of charadriiform birds.

UUID: http://zoobank.org/ca15ee81-09e8-4577-8beb-a362debf6636

Fossil fish are poorly represented in middle Lower Devonian deposits of the western United States. Here we describe vertebrate microremains from mid-Pragian levels in the Kobeh Member, McColley Canyon Formation, central Nevada. The species diversity of the assemblages is low and dominated by the acanthodian Nostolepis costata Goujet, 1976. This species is found in older (late Lochkovian–early Pragian) deposits in France and Spain and mid-Pragian or slightly younger deposits in Saudi Arabia. This distribution suggests dispersal to the west from the Armorica terrane around the south of Laurussia to the Nevada region, and southeastward to Arabia, on the northern margin of Gondwana.

A recent study on the fossil history of North American woodrats and their relatives suggested that the Neotomini includes two subtribes: the Neotomina (woodrats; Tsaphanomys, Neotoma, Hodomys, Xenomys) and Galushamyina (reprats: Protorepomys, Galushamys, Miotomodon, Repomys, Nelsonia). The extinct Miocene Lindsaymys was proposed as a possible early neotominan, but not formally included in the Neotomini. In other studies, two extinct genera, Basirepomys and Paronychomys, occasionally have been treated as related to neotominans, but their ancestry had not been formally explored in detail. We performed a phylogenetic analysis on representatives of all genera with 40 dental and mandibular characters likely to be preserved in fossil material. The analysis resulted in a single most parsimonious tree supporting a neotominan-galushamyinan tribal classification of the Neotomini, and securely placed Lindsaymys within the Neotomina. None of the Basirepomys and Paronychomys species or Protorepomys bartlettensis nested within the Neotomini. The three Basirepomys species, possibly a paraphyletic group, are not closely related to Repomys, and Paronychomys (minus P. shotwelli = Tsaphanomys shotwelli) is not closely related to Onychomys, but is a possible sister group to the Neotomini. With the understanding that further study may remove it from Protorepomys, P. bartlettensis is tentatively retained within the genus, representing a relatively underived species possibly ancestral to both neotominan clades. Neotoma species of the extinct subgenus Paraneotoma and extant Neotoma may be paraphyletic at the generic level, but that determination will require further study.

Kazachostylops occidentalis Nesov, 1987b, based on partial maxilla and dentary from the upper Paleocene Zhylga locality in South Kazakhstan, is redescribed. A new phylogenetic hypothesis of Arctostylopida is proposed based on phylogenetic analysis of 26 characters and 17 taxa. Kazachostylops is recovered as a sister taxon to the Arctostylopinae, the advanced clade of Asian and North American arctostylopids characterized by pseudohypocone on upper molars and reduced trigonid of lower molars, with the ectolophid being attached labial on the trigonid. Kazachostylops differs from more basal arctostylopids (Asiostylops, Allostylops, Bothriostylops, and Wanostylops) by higher-crowned molars, M1–3 metaconule absent, m1–3 entoconid connected with ectolophid by entolophid, and m2 wider than m1 and m3. Principal component analyses of the upper and lower dentition of arctostylopids show great distinctness of Kazachostylops from other members of the group. The arctostylopid taxa are reviewed, and the new genus Enantiostylops is erected for ‘Sinostylops’ progressus Tang and Yan, 1976 from the lower Eocene of China, because of uniquely concave parastylar area on upper molars.

UUID: http://zoobank.org/a46d8f29-fd73-4e59-88dc-fcc55b12d1d3

Oligocene landscapes of New Mexico were dominated by andesite stratovolcanoes and resurgent domes of ash-flow tuff (ignimbrite) cauldrons (Smith et al., 1985). This pervasive volcanism produced volcanic and volcaniclastic rocks that have been neglected by vertebrate paleontologists, so that, until now, no Oligocene vertebrate fossils have been discovered in New Mexico. This documents the initial results of vertebrate paleontological investigations of Oligocene rocks in New Mexico, a lower jaw of the oromerycid artiodactyl Montanatylopus matthewi, the first Oligocene mammal from the state. In this paper, CM = Carnegie Museum of Natural History and UNM = University of New Mexico.

Propeamussium (Parvamussium) holzense n. sp. and Propeamussium (Parvamussium) robinsonense n. sp. are described from the Upper Cretaceous Holz Shale Member of the Ladd Formation, Santa Ana Mountains, southern California. These species occur with Bostrychoceras elongatum (Whiteaves), Glyptoxoceras subcompressum (Forbes), and Inoceramus orientalus (Sokolow), which are indicative of a late medial Santonian age (Bostrychoceras elongatum Biochron). Propeamussium (Parvamussium) cowperi (Waring), from the Campanian Chatsworth Formation of the Simi Hills, southern California, is also redescribed and reillustrated for comparative purposes.

A single specimen of the new dictyonine hexactinellid species Verrucocoelia biswasi was collected from the Middle Eocene Fulra Limestone from Lakhpat Fort, Kutch, western India. The euretoid species is broadly bowl-shaped, 7–8 cm wide and 5–6 cm high, with walls of branched to weakly anastomosed tubes that extend upward and outward from a simple, unfluted, walled spongocoel. Skeletal strands diverge upward and outward from near the gastral surface of each tube. The sponge occurs in silty tan marl with abundant alveolinids and less common other large foraminifera, bivalves, and gastropods in sediments thought to have accumulated in a quiet, sheltered environment, possibly a lagoon.

A microfossil study of two boreholes, Araromi and Gbekebo (Geological Survey of Nigeria borehole numbers 1131 and 1132) (Figure 1), revealed the occurrence of Buntonia beninensis Reyment (1960, 1963) in the late Paleocene interval. This species was found to have forms with normal overlap and hinge element and forms with a reversal of these morphological features. In the former, the left valve is larger than the right, which bears the projecting terminal hinge element, whereas, in the latter, the larger valve is the right valve with the smaller left valve bearing the projecting terminal hinge element.

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.

The late Silurian Arceoaster hintei new genus new species (Asteroidea, Echinodermata) is based on a single complete specimen from the lower Hunton Group of southern Oklahoma. Overall ossicular arrangement enables assignment of the new genus to the Paleozoic stem-family Hudsonasteridae; however, Arceoaster n. gen. is homeomorphic with members of the post-Paleozoic crown-group Goniasteridae. Because Arceoaster n. gen. is a hudsonasterid, and because similar morphologic expressions are not known among described taxa from later in the Paleozoic or the early Mesozoic, similarities between Arceoaster n. gen. and later genera are homoplastic, thereby providing an example of iterative evolution within Asteroidea. The Arceoaster n. gen. specimen is associated with a rich and diverse invertebrate fauna typical of its time interval and environmental setting; nothing suggests an unusual habitat. Selective pressures leading to homoplasy are conjectural, although robust construction among extant asteroids has been associated with a defensive life strategy.

UUID: http://zoobank.org/b1d8461d-7e54-43cc-8719-97304ca3fd7a

Graptolites from the latest Ordovician to the earliest Silurian rocks of northwest Peninsular Malaysia are described and reviewed. The fossils were collected previously by C. R. Jones and presently by the authors inside the black mudstones from the basal section of Tanjung Dendang Formation in Pulau Langgun, Langkawi, which comprises assemblages from the Hirnantian Metabolograptus extraordinarius Biozone to the Rhuddanian Akidograptus ascensus–Parakidograptus acuminatus Biozone. The latest Ordovician strata also include a Hirnantia fauna bed between the Metabolograptus extraordinarius and Metabolograptus persculptus biozones, in which shelly fossils such as Mucronaspis sp. could be recovered. A revised graptolite biozonation is proposed for the latest Ordovician to the earliest Silurian succession of northwest Peninsular Malaysia. This interval is significant for understanding the extent of mass extinction events happening right at the end of the Ordovician period and subsequent faunal change in the region.