The origin and affinity of the problematic Nuia Maslov is reappraised from exceptionally preserved specimens in Upper Cambrian (Sunwaptan) rocks of the Llano Uplift, central Texas. Nuia is suggested to be a radial calcitic ooid that has nucleated on fragments of reworked filamentous calcimicrobes rather than a separate microorganism as has been assumed previously. Nuia is found predominantly in intrareef grainstone accumulations, as well as in interreef grainstones, invariably accompanied by other bioclastic debris showing similar radial calcite ooid overgrowths.

Three productidine brachiopods of Haydenella, Paraplicatifera, and Compressoproductus are recovered from the Tak Fa Formation (Wordian, Middle Permian) of the upper Saraburi Limestone Group exposed at Khao Wong of central Thailand (the western margin of the Indochina Terrane). The latter two genera are new to the Permian of Thailand, and the new species Paraplicatifera thaica is proposed herewith. Some taxonomic and nomenclatural problems in relation to the three genera are discussed. The assemblage suggests endemism for a Middle Permian marine faunule of the Indochina Terrane.

Three species of the Paleozoic coral Palaeacis are described from northeastern Oklahoma and northwestern Arkansas. Included are the Chesterian species P. carinata Girty and P. snideri n. nom., a replacement name for the junior homonym P. cuneata Snider, and the Desmoinesian? species P. erecta n. sp. Coralla of each species exhibit two types of microstructure that characterize two skeletal zones. The outer skeletal zone is composed of numerous parallel trabeculae, mostly between 0.2 and 0.3 mm in diameter, that lie perpendicular to, and have their accretionary surfaces on, the exterior surface of the corallum. Trabeculae are closely spaced laterally and are not organized into rows except uncommonly on the distal portion of some coralla. Where trabeculae coalesce into parallel rows, ornamentation on the corallum exterior consists of parallel ridges or rows of small nodes. Where trabeculae are irregularly arranged, external ornamentation consists of irregularly disposed nodes. The inner skeletal zone consists of radially fibrous stereoplasm arranged into discrete septal spines that coalesce into irregularly developed septal ridges in each calice. In P. erecta, septal spines merge into continuous layers of fibro-normal stereoplasm in some places. On the basis of microstructure, corallum morphology, and external ornamentation P. carinata and P. snideri can be allied with P. axinoides Smyth and P. robusta Webb. Palaeacis erecta falls within the same group on the basis of microstructure and ornament, but has a unique corallum morphology.

Two distinct types of skeletal attachment occur in these Palaeacis species. Palaeacis carinata and P. snideri exhibit an encrusting attachment surface that results in a prostrate growth habit wherein smaller substrates were entirely engulfed, producing free-living coralla. Palaeacis erecta exhibits a small, circular attachment surface and an erect growth habit wherein most skeletal accretion occurs perpendicular to, and away from, the substrate. The substrate is not engulfed and the corallum remains attached and sessile throughout astogeny. Palaeacis erecta is, to date, the only Palaeacis species known to possess this erect, sessile growth form.

Clathrodictyids are the most abundant stromatoporoids in the Upper Ordovician Xiazhen Formation (middle to upper Katian) of South China. A total of nine species belonging to four clathrodictyid genera are identified in the formation, including Clathrodictyon idense Webby and Banks, 1976, Clathrodictyon cf. Cl. microundulatum Nestor, 1964, Clathrodictyon cf. Cl. mammillatum (Schmidt, 1858), Clathrodictyon megalamellatum Jeon n. sp., Clathrodictyon plicatum Webby and Banks, 1976, Ecclimadictyon nestori Webby, 1969, Ecclimadictyon undatum Webby and Banks, 1976, Camptodictyon amzassensis (Khalfina, 1960), and Labyrinthodictyon cascum (Webby and Morris, 1976). The clathrodictyid fauna in the Xiazhen Formation is very similar to those from both New South Wales and Tasmania, although the latter two Australian regions do not share any common clathrodictyid species during the Late Ordovician. The paleobiogeographic pattern indicates that the northward drift of South China resulted in a favorable environment for the migration of clathrodictyids from other peri-Gondwanan terranes to South China. In addition, these peri-Gondwanan clathrodictyid species hosted various endobionts, representing a variety of paleoecological interactions. The high abundance and species-level diversity of clathrodictyid species presumably increased the substrate availability of suitable host taxa, judging from the diverse intergrowth associations between clathrodictyids and other benthic organisms. These paleoecological interactions between stromatoporoid and other organisms are known from the Late Ordovician and became more abundant and widespread in the Siluro–Devonian. Overall, the Late Ordovician clathrodictyid assemblage in South China demonstrates one of the highest species-level diversities among all peri-Gondwanan terranes and represents a precursor of the complex, clathrodictyid-dominated communities of later metazoan reefs during the Great Ordovician Biodiversification Event.

UUID: http://zoobank.org/6063c47d-cb77-4a03-98cf-b2354656dea6

A new eocrinoid ?Ubaghsicystis sp. from the middle Cambrian (Series 3, Stage 5) Burgess Shale is reported based on a single known specimen. This species extends the stratigraphic range of columnal-bearing eocrinoids in Laurentia significantly from Cambrian Stage 7 (Guzhangian) to Stage 5. It increases the diversity of echinoderms in this well-known fossil-Lagerstätte, provides the oldest evidence of columnal-bearing eocrinoids from Laurentia, and further documents the cosmopolitan distribution of middle Cambrian echinoderm clades.

The Meade Basin, SW Kansas, yields a rich vertebrate fossil record from the late Cenozoic. Here, we review fossil ground squirrels (Sciuridae) from the region as a contribution to the broader Meade Basin Rodent Project. We recognize 14 species in seven genera: two species of giant ground squirrels (Paenemarmota Hibbard and Schultz, 1948) from the early Pliocene, and at least 12 species in six extant genera (Ammospermophilus Merriam, 1892; Otospermophilus Brandt, 1844; Ictidomys Allen, 1877; Poliocitellus Howell, 1938; Urocitellus Obolenskij, 1927; Cynomys Rafinesque, 1817) from the Pliocene–Pleistocene sequence, including the first regional records of Ammospermophilus. Based on dental morphology and the ecology of modern congeners, we interpret faunal change through the sequence as primarily reflecting a shift from a Pliocene assemblage of “southwestern” taxa with granivorous/omnivorous diets (relatively low-crowned, transversely narrow cheek teeth) in warm and at least occasionally dry shrub or shrub-steppe habitats (Ammospermophilus, Otospermophilus, Ictidomys meadensis [Hibbard, 1941a]), to a Pleistocene temperate assemblage of grazing taxa that either exhibited relatively high-crowned, transversely wider cheek teeth (Urocitellus, Cynomys, Ictidomys tridecemlineatus [Mitchill, 1821]) or were otherwise dependent on grassland habitats (Poliocitellus). The early Pleistocene Borchers assemblage was transitional in this regard, heralding a “revolution” observed as well with other clades in the Meade Basin rodent community. This interpretation is broadly congruent with evidence of Pliocene climatic change and the staged development of regional grasslands, with the modern proportion of C3/C4 plants established in the Meade Basin during the early Pleistocene.

Falloaster anquiroisitus new genus new species (Asterozoa, Echinodermata) is described from the Floian (Early Ordovician) Garden City Formation of Idaho. The new taxon is known from a single small specimen. Because of weathering, remaining disk elements are incomplete. Dorsal surfaces of the ambulacral ossicles of two arms are available, one well preserved, whereas those of a third arm expose the ambulacrals essentially as they would appear in ventral view. Ambulacral ossicles were all but entirely lost on the remaining two arms.

Albeit asterozoan, F. anquiroisitus is not assignable at the class level. It is suggestive of the Asteroidea in presence of a domal disk, five abruptly tapering triangular, arched arms, and ambulacral ossicles vaulted to form a furrow. Ambulacral morphology, including the presence of very large podial pores, is unlike that of early asteroids. In addition, no adambulacral or other virgal-series derivatives are present; ambital framework ossicles are absent; a single series of enlarged, plate-like arm ossicles, one series on each side of the arm, come together at the arm midline; and the plate-like series were supported laterally by recurved ambulacral margins. Only remnants of the disk near the periphery survive, these of overall expression unlike any other echinoderm, including asterozoans. The mouth frame is unknown. Falloaster anquiroisitus is argued to represent an extinct lineage apart from the four recognized asterozoan classes, thereby joining a limited number of other problematic early Asterozoa.

UUID: http://zoobank.org/a13a5417-44b6-4ac3-90cf-9dc8fb5902bd

The sparse record of Cretaceous crocodyliforms in Australia comprises only three species, all within the genus Isisfordia. Isisfordia duncani Salisbury et al., 2006 is from the Albian–Turonian Winton Formation of Queensland, and both Isisfordia molnari Hart et al., 2019 and Isisfordia selaslophensis Etheridge, 1917 have been described from opalized material from the Cenomanian Griman Creek Formation of New South Wales. Here, we describe new cranial and postcranial material, including the most complete crocodyliform skeleton from the Cretaceous of New South Wales, which is assigned to Isisfordia cf. I. selaslophensis. We also reappraise previously described crocodyliform material from the same locality. We find that much of this material displays features that are consistent with Isisfordia.

The present study of the Eifelian icriodid conodonts is based on collections from Belarus and the Michigan Basin (USA). It is here proposed that forms originally included in Icriodus orri Klapper and Barrick, 1983 can be attributed to I. retrodepressus Bultynck, 1970, Icriodus orri sensu stricto, and Icriodus michiganus new species, each displaying a distinct morphology, stratigraphical range, and geographic distribution. Icriodus retrodepressus, characterized by a triangular spindle, deep depression in its posterior part, and a well-pronounced spur and antispur, appeared in the lower partitus Zone of the lowermost Eifelian and disappeared in the upper Eifelian kockelianus Zone. Icriodus michiganus n. sp., distinguished by a lachrymiform spindle with a shallow posterior depression, ranges from the lower costatus Zone to the upper kockelianus Zone. Icriodus orri differs from the other two species by the occurrence of transverse denticle rows with lateral denticles displaying sharp edges. It ranges from the upper kockelianus Zone to the ensensis Zone of the uppermost Eifelian. Icriodus retrodepressus first occurred in the European part of the Euramerican continent and later migrated into the North American area. Icriodus michiganus n. sp. has been found in the interior part of the North American Craton and near the eastern Euramerican margin. Icriodus orri occurs in the North American interior, in British Columbia (Canada), and in the eastern part of Euramerica (Belarus). The introduction of I. retrodepressus can be related to the transgressive Choteč Event, whereas that of I. orri to a transgressive stage of the Ie eustatic cycle.

Among the several evolutionary lineages of the baleen whales (Mysticeti), the eomysticetids are an ancient successful family that retain possibly nonfunctional teeth and functional baleen, a transitional stage between toothed and baleen-assisted filter-feeding mysticetes. The patchy fossil record leaves gaps in eomysticetid paleobiology interpretations, but their diversity and widespread geographical distribution can be a relevant proxy to understanding the evolution of crown Mysticeti. Here we describe a new baleen whale, Echericetus novellus n. gen. n. sp., from the Oligocene of Mexico (slightly older than 27.95 million years ago). This new taxon has morphological features that show its affinity to Eomysticetidae, such as the intertemporal region longer than wide, the elongate and oval temporal fossa, and a well-developed and lobate coronoid process of the mandible. Similarly, our cladistic analyses confirm the inclusion of Echericetus in the Eomysticetidae. Echericetus reinforces our notion of the eomysticetid diversity and disparity. Geographically, the existence of Echericetus from Mexico also indicates that eomysticetid inhabited subtropical regions in the Northern Hemisphere. Last, our discovery of a new eomysticetid from the Oligocene of Mexico provides new insights into the distribution patterns and habitat use of Eomysticetidae, essential to further explain the demise of this transitional lineage between toothed and baleen-bearing whales.

UUID: http://zoobank.org/00cfc802-e2da-465c-9bb6-59347be00164

The Hawkesbury Sandstone (Hawkesbury Series, Sydney Basin) on the southeastern coast of New South Wales, Australia, preserves a depauperate but important vertebrate tetrapod body-fossil record from the Early and Middle Triassic. As with many fossil sites around the world, the ichnological record has helped to shed light on the paleoecology of this interval. Herein, we investigate historical reports of a trackway pertaining to a putative short-tailed reptile found at Berowra Creek in the 1940s. Reinvestigation of the surviving track-bearing slabs augmented by archival photographs of the complete trackway, suggests that these impressions, which consist primarily of didactyl tracks (plus less common monodactyl and tridactyl traces), represent the earliest example of a swimming tetrapod found in Australia. Another isolated specimen (possibly from a nearby locality at Annangrove) appears to represent similar didactyl swim traces of a second, larger individual. Although the identities of the trackmakers are unknown, the Berowra Creek individual had an estimated body length of between ~80 cm (short-coupled) and 1.35 m (long-coupled), and produced the subaqueous trackway while travelling upslope (against the current) on a sandbar within a braided river system of the Hawkesbury Sandstone. These trackways partially resemble amphibian swim traces in the so-called Batrachichnus C Lunichnium continuum, but appear to represent a unique locomotion trace. This reanalysis of the Berowra Creek trackway provides insight into the locomotion of tetrapods of the Triassic Hawkesbury Series, which remains a poorly understood aspect of their life history.

Rare scales of agnathan thelodonts Paralogania ludlowiensis and Thelodus sp. cf. T. parvidens, or alternatively Thelodus macintoshi, and acanthodian fishes Nostolepis striata, Gomphonchus sp., Gomphonchoporus sp. aff. G. hoppei, and Machaeraporus stonehousensis (Legault) n. gen., plus acanthodian fin spines, teeth and tooth whorls have been identified from the upper Moydart and Stonehouse formations near Arisaig, Nova Scotia. The assemblage agrees well with the late Silurian (uppermost Ludlow–Přídolí) age assigned to these strata based on invertebrate assemblages, and the vertebrate taxa show affinity with British and Baltic faunas of this age. All vertebrate-bearing strata were deposited in various positions off the western shores of the Avalonia terrane during or after its collision with Laurentia.

The barnacle fauna of the Miocene Bear Lake Formation of the Alaska Peninsula includes Chirona (Chirona) alaskana n. sp., and three species of Balanus Da Costa conspecific with or related to the extant species Balanus balanus (Linnaeus), B. nubilus Darwin, and B. crenatus (Bruguière). Although the Bear Lake fauna lived in warm temperate waters, its modern counterparts are found primarily in boreo-arctic and cool temperate regions of the North Pacific and North Atlantic Oceans. Miocene barnacle faunas in Japan are similar to those of the Alaska Peninsula, lacking relatives of B. nubilus, but including Semibalanus Pilsbry, which does not appear until the Pleistocene in the eastern Pacific. Elements of this boreo-Arctic fauna do not appear in the North Atlantic basin until the Pleistocene, suggesting migration of the fauna into the Atlantic with the opening of the Bering Straits.

South Canyon, located in the New Pass Range in central Nevada (Fig. 1), is one of the most important localities for Upper Triassic marine invertebrates in North America. This site yields very rich ammonoid faunas, as well as cnidarians (Muller, 1936; Stanley, 1979; Roniewicz and Stanley, 1998), foraminifers (Gazdzicki and Stanley, 1983), bivalves (Waller and Stanley, 1998, 2005; Hopkin and McRoberts, 2003), and brachiopods.

Rugose and tabulate corals from the Lower Permian (Wolfcampian) part of the Bird Spring Group in the Providence Mountains, San Bernardino County, southeastern California, comprise eight species in eight genera. Heritschioides mckassoni n. sp. is the lowest stratigraphic record for this index genus on the undoubted shelf of western North America. Paraheritschioides applegatei n. sp. is the first record for the genus in southern California. Neomultithecopora providensis n. sp. is a second species for the genus in the southern Great Basin. The other five species provide close ties to previously described faunas from the Spring Mountains and the Arrow Canyon Range of southwestern and southeastern Nevada. The combined Wolfcampian coral faunas of these three areas are somewhat closer at the genus and species level to the McCloud Limestone Wolfcampian faunas of northern California than to the Wolfcampian shelf faunas in east-central Nevada. Additional species present in the combined faunas are known originally from the Wolfcampian of central Nevada and Kansas and a genus is not otherwise known south of British Columbia. The faunas suggest a subprovince of the Durhaminid Coral Province for the southern California and southern Nevada area and perhaps imply partial isolation from the more northerly parts of the province by land barriers such as the Antler Highlands.

New material of the poraspid Alainaspis platyrhina Elliott and Dineley has made it possible to provide a more extensive reconstruction of this animal. It is now clear that an elongated branchial opening was present below the lateral lamina and that a well-developed post-branchial lobe was present. No branchial plate has been identified and this may have been fused to the dorsal shield, forming the ventral lamina. The lateral lamina is now seen to terminate in a rounded angle before the posterior margin of the shield. Several ventral shields with similar ornament are identified as belonging to A. platyrhina. These are broad and deep and are consistent with the original interpretation of this animal as a filter feeder. One similar shield with a coarser ornament is tentatively assigned to the closely related species Boothiaspis ovata Broad.

Triassic lungfish (Dipnoi) have been extensively documented from the Gondwanan continental and marine shelf deposits of Africa and Madagascar (Teixeira, 1949; Lehman et al., 1959; Beltan, 1968; Martin, 1979, 1981; Kemp 1996), Australia (Kemp, 1993, 1994, 1997a, 1998), India (Jain et al, 1964; Jain, 1968), and Antarctica (Dziewa, 1980). Numerous records also exist from Laurasian landmasses including Europe (Agassiz, 1838; Schultze, 1981), North America (Case, 1921) and central and eastern Asia (Liu and Yeh, 1957; Vorobyeva, 1967; Martin and Ingavat, 1982). By comparison, nothing is known of contemporary lungfish fossils from the Middle East. Thus, the recent recovery of a single tooth plate representing a new geographic occurrence of the genus Ceratodus Agassiz, 1838 from paralic marine deposits of the Jilh Formation, a latest Anisian to lower Carnian unit that crops out along the eastern margin of the Proterozoic Arabian Shield in central Saudi Arabia (Fig. 1), is significant because it provides the stratigraphically oldest record of dipnoans from the Arabian Peninsula.

The wall of Michelinia meekana Girty is composed predominantly of lamellae that are approximately parallel to the median dark line, confirming its placement in the genus Michelinia s.s. The presence of a Praemichelinia-type microstructure in some parts of the wall is a recurrence of primitive architecture that suggests derivation of Michelinia from Praemichelinia.

In situ colonies of Bulmanicrusta? sp. encrusting the surface of a hardground from the Upper Ordovician Bull Fork Formation provide the first glimpse of the full colony form, habitat, and faunal associates of a crustoid graptolite. Bulmanicrusta? sp. exhibits a runner-type colony form suited to rapid expansion over hard substrates, indicating it was an opportunistic member of the hardground community. This community also included two bryozoans (“Proboscina” and Amplexopora), Cornulites, and crinoids. The Bulmanicrusta? sp. specimens contain numerous graptoblasts (small, thick-walled vesicles) in organic connection with the colony. These objects are located at branch termini and confirm that graptoblasts were not pathological features, but probably were resting cysts produced by the crustoid colony as a normal part of its life cycle. Thus, the presence of graptoblasts supports the interpretation that the Caesar Creek crustoid was adapted to ephemeral or disturbance-prone environments.

Relative differences between environmentally controlled variation and genetically controlled variation are important when investigating morphologic variation in general, especially when establishing species concepts. The colonial nature of bryozoans provides a means for distinguishing between the two sources; variation can be partitioned into within-colony (microenvironmental) and among-colony (environmental + genetic) components. For the Paleozoic order Cryptostomata, biologically and taxonomically significant morphologic characters are well defined and methods for recognizing morphotaxa are well established.

The importance of within-colony variation to the morphometric treatment of fenestrate species was assessed after the discovery of a large specimen of Hemitrypa sp. Variation within the colony was compared to variation among and within two congeneric species. The distribution of study segments across the colony allowed assessment of variation both along the growth axis and laterally between segments of approximately equivalent generational age. Repeatability of methods was assessed using data measured independently from identical segments by three workers.

Variation within the large colony is less than variation among congeneric species, indicating that genetic differences among species exceed variation resulting from combined phenotypic and genotypic sources within species. Neither astogenetic nor ontogenetic morphologic gradients are recognized. Variation between data collected from identical segments by pairs of workers falls within the range of variation for the entire colony. Thus, multiple workers can reproduce data to the finest level of meaningful resolution. Cryptostome morphospecies concepts are validated.

The potential for partitioning genotypic versus environmental variation in reduced, multidimensional morphospace is reinforced. Studies of microevolution and speciation may be designed that account for these factors.