Invertebrate Fossils Research Articles

Revised stratigraphy of the middle Simcoe Group (Ordovician, upper Sandbian–Katian) in its type area: an integrated approach

The Upper Ordovician Bobcaygeon Formation of southern Ontario is a widespread unit that spans the Sandbian–Katian stage boundary and contains exceptionally preserved invertebrate fossil assemblages, including the famed ‘Kirkfield echinoderm fauna.’ However, the precise correlation of this interval remains poorly understood. This paper presents new data on high-resolution sequence and carbon isotope chemostratigraphy of the Bobcaygeon interval based on new quarry exposures and introduces refined definitions of unit boundaries based on allostratigraphic criteria. Sequence, chemo-, and biostratigraphic evidence indicate that the Bobcaygeon Formation represents a composite unit as it encompasses a major erosional unconformity. The Coboconk and Kirkfield formations, described in the early 20th century, were merged into a single unit, the Bobcaygeon, out of concern that the original lithostratigraphic divisions would be conflated with biostratigraphic zones of the same names. However, these biostratigraphic zones are no longer favoured, and the lower member of the Bobcaygeon is here elevated again to the status of formation (Coboconk Formation) and represents the uppermost portion of the Sandbian M4 sequence. The middle and upper members of the Bobcaygeon, herein reassigned to the Kirkfield Formation, represent the upper Sandbian to lower Katian M5A and M5B sequences recognized widely in the eastern and central United States. The term Bobcaygeon is retained and elevated to the rank of subgroup. The Kirkfield Formation is divided into three members and contacts are refined, placing a 1–2 m transgressive grainstone at the base of each sequence. These units are correlated with equivalent strata of New York and the Cincinnati Arch.

First Upper Cretaceous dinosaur track assemblage from Jordan (Middle East) – preliminary results

Dinosaur tracks from Jordan (Middle East) have only been briefly reported in geological overview papers and books. We present here the first description and documentation of Jordanian dinosaur tracks based on a new tracksite from the south-central part of the country. The track-bearing strata belong to marginal marine (tidal flat) deposits of the Na’ur Formation (Upper Cretaceous, Cenomanian). This unit largely consists of well-bedded limestones, dolomites and marls that contain abundant marine invertebrate fossils such as bivalves, ammonites and foraminifers. The dinosaur ichnofauna occurs on four different levels and comprises abundant theropod tracks and trackways as well as isolated sauropod and ornithopod tracks. Theropod trackways consist of two different morphotypes. Morphotype 1 is tridactyl (26 cm pes length) and with a broad, but short metatarsal area and resembles the ichnogenus Picunichnus from the Lower Cretaceous (Albian) of Argentina. Morphotype 2 (36 cm pes length) has extensive and narrow metatarsal impressions continuously occurring along regularly-spaced trackways. This suggests either a plantigrade movement of the trackmaker or reflects preservational factors. By their overall-shape with thin digits, Morphotype 2 resembles described penetrative tracks suggesting a strong influence of the substrate. Sauropod tracks are relatively small (40 cm pes length) and show low heteropody with a kidney-shaped manus imprint, pointing to a Sauropodichnus -like form. The single ornithopod pes track (18 cm in length) is similar to material described as Ornithopodichnus from the Lower Cretaceous of Korea. Due to the incomplete material of sauropod and ornithopod prints, no concrete assignment is given to this material and further study is needed. The presence of dinosaur tracks proves a temporary subaerial exposure of the surface whereas the main part of the Na’ur Formation is dominated by subaqueous activity of marine faunas.

Late Neogene insect and other invertebrate fossils from Alaska and Arctic/Subarctic Canada

Late Neogene insect and other invertebrate fossils from Alaska and Arctic/Subarctic Canada

Brachiopod fauna from Longá Formation (Upper Devonian), State of Piauí, NE Brazil

ABSTRACT In the Parnaíba Basin, Devonian marine invertebrate macrofossils occur mainly in the Pimenteira Formation (Picos and Passagem Members), and are scarcer in the Longá Formation, which has poor preservation of the samples and a limited amount of material available to be analysed. There has been, to date, no description or proper taxonomic classification of its body fossils, despite the limited diversity. Brachiopod taxonomy is reviewed and analysed herein for the first time. It was possible to describe a new species from the order Orthotetida, belonging to the genus Schellwienella, named Schellwienella justinianoi n. sp. We also confirmed the presence of the inarticulate brachiopods ‘Lingula’? and Orbiculoidea?, which have been tentatively identified by some authors. We emphasise the importance of the conservation of this Brazilian Geoheritage both in situ and ex situ. Future field studies are needed to document the entire biota of the Longá Formation, to elucidate the palaeobiogeographic affinities of Devonian invertebrate fossils of Brazil, and related faunas in South America, and to test ideas of marine connections between these areas. These studies provide insights regarding the impacts caused by late Devonian (Kellwasser and Hangenberg) biocrisis on the Brazilian fauna, and its palaeoecological aspects. http://www.zoobank.org:act:1CC9A9C8-D6A6-4BD7-85AD-3853FEE29323

New evidence of a Campanian age for the Cretaceous fossil-bearing strata of Cape Marsh, Robertson Island, Antarctica

Cape Marsh, located on the eastern end of Robertson Island to the east of the Antarctic Peninsula, exposes an isolated outcrop of Upper Cretaceous sedimentary strata. The outcrop is approximately 120 km southwest of the much better-studied exposures of similar age on and around James Ross Island (JRI); as such, its remoteness has complicated logistical access to the site and hindered geologic correlations on a regional scale. Here we present the results of fieldwork conducted in 2016 that yielded a more diverse invertebrate fossil assemblage than had been previously recognized, in addition to new U–Pb detrital zircon and magnetostratigraphic data. The invertebrate fauna, particularly the ammonites and inoceramids, support a biostratigraphic correlation of the upper Cape Marsh strata to Ammonite Assemblage 7 previously established on JRI. Detrital zircon U–Pb analysis conducted on a sandstone sample from the same strata indicates a maximum depositional age of 74.2 ± 1.1 Ma, and magnetostratigraphic interpretation of the lower strata suggest a normal magnetochron. These results are all consistent with a Campanian age for the deposition of the upper strata at Cape Marsh, and deposition during magnetochron C33N for the lower layers. However, a slight age inconsistency between the biostratigraphic correlation and the detrital zircon-derived maximum depositional age may imply that the fossils are reworked. Regardless, these new data allow us to correlate the strata at Cape Marsh to the Santa Marta and Rabot formations (or possibly the lower part of the Snow Hill Island Formation) in the northern part of the James Ross Basin.

Fossil‐Lagerstätten, palaeoecology and preservation of invertebrates and vertebrates from the Devonian in the eastern Anti‐Atlas, Morocco

In some Devonian strata in the eastern Anti‐Atlas, fossil invertebrates are abundant, display a high taxonomic diversity and indicate many shifts in palaeoecology. This is reflected in changes in faunal composition of invertebrates and vertebrates. Fossils of jawed vertebrates of late Lochkovian and younger age have been recorded and are relatively common with their abundance and diversity increasing towards the Late Devonian. Environmental changes in the Devonian also left their mark in the preservation of vertebrates and invertebrates from the Anti‐Atlas, which varies strongly through time and regionally. This variation partially reflects environmental changes linked with the evolution of small marine basins during the disintegration of the continental shelf of Gondwana in this region, fluctuations of the regional sea level and other environmental changes. To improve our understanding of these ecological changes, of shifts in preservation through the succession and of the formation of Fossil‐Lagerstatten, we analysed the mineral composition of some invertebrate and vertebrate samples of Devonian and Early Carboniferous age by Raman spectroscopy and X‐ray diffraction. Additionally, we characterized some of these Fossil‐Lagerstatten using palaeontological and sedimentological parameters. We examined eight Devonian Konzentrat‐Lagerstatten and two Konservat‐Lagerstatten with soft‐tissue preservation (the Famennian Thylacocephalan Layer and the Hangenberg Black Shale of the southern Maider). The last two are the first Konservat‐Lagerstatten described from the Devonian of North Africa. The taphonomic and oceanic settings suggest that these Konservat‐Lagerstatten are formed because of stagnation (related to vertical restriction of water exchange and water depth rather than limited spatial water exchange and a lateral restriction) in the relatively small Maider Basin with limited water exchange with the neighbouring Tafilalt Basin. The temporally low oxygen levels in the Maider Basin are a possible reason for the reduced chondrichthyan diversity (missing demersal and shallow water species) compared to the Tafilalt Platform.

Carboniferous deposits of northern Sierra de Tecka, central-western Patagonia, Argentina: paleontology, biostratigraphy and correlations

A narrow upper Paleozoic belt crops out in the northern tip of Sierra de Tecka through the Quebrada de Güera-Peña (Patagonia, Argentina). There, black shales of the Pampa de Tepuel Formation contain marine fossil invertebrates previously listed as belonging to the “Levipustula” fauna. Material recently recorded by the authors comprises, in order of abundance, gastropods [Glabrocingulum (Glabrocingulum) poperimense (Maxwell), G. (Stenozone) argentinum (Reed), G. (Stenozone) sp., Peruvispira teckaensis sp. nov., Ananias riccardii Pinilla], bivalves [Nuculopsis (Nuculopsis) patagoniensis González, Phestia tepuelensis González, Streblochondria sueroi González, Streblopteria sp.], conulariids [Paraconularia cf. ugartei Cúneo and Sabattini], brachiopods [Amosia sueroi Simanauskas, Languigneotus laevicaudatum (Amos), Beecheria patagonica Amos], trilobites [Australosutura argentinensis Hahn and Hahn], cephalopods [Pseudoorthoceratidae Flower and Caster, Sueroceras? sp., Mitorthoceras? sp.], and rugose corals [?Lophophyllidiidae Moore and Jeffords]. In addition, the present study includes the new key brachiopods Languigneotus dammanorum gen. et sp. nov. and Tuberculatella waterhousei sp. nov. from younger localities of the Tepuel-Genoa Basin. The Languigneotus laevicaudatum and Languigneotus-Verchojania subzones (late Pennsylvanian) are proposed herein to replace the former Tuberculatella Zone. In addition, previous stratigraphic relationships and correlations of the study section with the Arroyo Pescado (Estancia Ap Iwan) and Esquel areas are discussed. The general stratigraphic profile of a glacial-related section cropping out at Estancia Ap Iwan includes lower conglomeradic beds, which are reinterpreted as early Jurassic in age, and glacimarine levels that are partially equivalent to the Pampa de Tepuel Formation but older than those of Quebrada de Güera-Peña. A correlation of the Esquel Formation with the Arroyo Pescado Formation and other contemporaneous units on the paleopacific margin is assessed, implying that the Esquel Formation should be segregated from the Tepuel Group. The Esquel and Arroyo Pescado formations can be regarded as the basement of the glaciomarine column of the Tepuel-Genoa Basin.

A new microinvertebrate with features of mites and tardigrades in Dominican amber

AbstractFrom time to time, small, fragile, previously unknown fossil invertebrates are found in specialized habitats. Occasionally, as in the present case, a fragment of the original habitat that existed millions of years ago is also preserved. The present article describes a previously unknown microinvertebrate in Dominican amber that cannot be placed in any group of extant invertebrates. Placed in a new family, genus, and species, the fossil shares characters with both tardigrades and mites, but clearly belongs to neither group. The several hundred fossil individuals preserved in the amber shared their moist, warm habitat with pseudoscorpions, nematodes, fungi, and protozoa. The large number of fossils provided additional evidence of their biology, including their reproductive behavior, developmental stages, and food. While there is no extant group that can accommodate these fossils, and we have no knowledge of any extant descendants, this discovery shows that unique lineages of minute invertebrates were surviving in the mid‐Tertiary.

The Devonian-Cretaceous fossil record of “conchostracans” of Africa and their paleobiogeographic relationships with other Gondwanan faunas

The main objective of this work is to present a survey of the fossil record of “conchostracans”, a group of continental (also occasionally from brackish and marine sequences) fossil invertebrates, recorded from Africa, to explore relationships among these taxa and those recorded from other paleocontinents, and to assess the potential for the African “conchostracan” records to provide insight on paleobiogeographic connections within Gondwana. This work is focused on “conchostracans” (laevicaudatans, spinicaudatans and cyclestheriids), because “conchostracans” are one of the most widely documented groups in the Phanerozoic continental sequences. A clear signal of taxonomic change is recovered within the African fauna. Leaiids, lioestheriids and palaeolimnadiids characterize African Paleozoic-Triassic strata, whereas afrograptids, fushunograptids and palaeolimnadiopseids characterize African Mesozoic strata. The relationship among African and other Gondwanan taxa is considered, and the potential for “conchostracans” as paleobiogeographic indicators is evaluated. Biogeographic analysis is based on the compiled data about the African “conchostacans” fossil record with specific consideration of some emblematic groups (Leaiidae, Paleolimnadidae, Vertexiinae, and Afrograptidae). Key dispersal pathways may have operated. During the Devonian to Triassic, records suggest four different faunal interchanges between Africa and Australia, Europe, South America, and India. During the Jurassic to Cretaceous, records suggest five different faunal interchanges between Africa and South America, Europe, Asia, India and Antarctica marked by different emblematic taxa.

Synchrotron X-ray tomographic imaging of embedded fossil invertebrates in Aboriginal stone artefacts from Western Australia: Implications for sourcing, distribution and chronostratigraphy

Eocene fossiliferous chert is a distinctive rock used in the manufacture of stone artefacts commonly found in archaeological sites in southwestern Western Australia (WA). In this study, we employ non-destructive high-resolution X-ray computer tomographic (CT) imaging at the Australian Synchrotron to map and identify embedded bryozoan (and other) fossils within archival artefact samples and potential source material from offshore drill cores in the Perth Basin and from the Nullarbor Plain to the east. Analysis of synchrotron data confirmed the presence of Cellaria, Porina, Quadricellaria, Reteporella, Siphonicytara, Trigonopora, and Idmonea species in chert samples from as far afield as Exmouth Gulf in the north west of WA, Esperance in the south and inland as far as the Goldfields region of WA. This widespread distribution of fossiliferous chert over 1800 km is significantly greater than previously documented and the bryozoan fingerprinting of geological source and artefact material indicates that a potential source within the Eucla Basin located in the SW corner of WA cannot be discounted. In addition, the association of one chert artefact on Doole Island (Exmouth Gulf) with shell midden material dated between 2500 and 770 yr BP also questions the use of fossiliferous chert as a late-Pleistocene-early Holocene chronological marker. The advantages and limitations of synchrotron CT imaging for characterising and sourcing fossiliferous chert are also discussed, with further research warranted on the distribution and probable long-distance trade of this idiosyncratic material.

Late Eocene (Priabonian) elasmobranchs from the Dry Branch Formation (Barnwell Group) of Aiken County, South Carolina, USA

Author(s): Cicimurri, David J.; Knight, James L. | Abstract: A survey of the Eocene (Priabonian) Dry Branch Formation exposed in Aiken County, South Carolina, resulted in the collection of thousands of fossil teeth and bone fragments. Two sites located near the city of Aiken proved to be particularly productive, and 24 species of elasmobranchs, 11 osteichthyans, and three reptiles (one crocodilian and two turtles) have been identified. Herein we focus on the elasmobranch species (17 sharks and seven rays) that are part of the assemblage, which includes a new species of daggernose shark, Isogomphodon aikenensis n. sp. Cicimurri and Knight. The fossils are derived from the upper part of the Dry Branch Formation, and the fossiliferous strata accumulated within a high energy nearshore marine depositional environment that was influenced by a river system. Based on the vertebrate and invertebrate fossils we identified, the water depth was less than 40 m, and surface water temperature was at least 22° C . Elasmobranch species composition is similar to other late Eocene elasmobranch assemblages reported from the Gulf and Atlantic Coastal plains, particularly Georgia, and several of the taxa indicate affinities to the Tethyan region.

Facies selectivity of benthic invertebrates in a Permian/Triassic boundary microbialite succession: Implications for the "microbialite refuge" hypothesis.

Thrombolite and stromatolite habitats are becoming increasingly recognized as important refuges for invertebrates during Phanerozoic Oceanic Anoxic Events (OAEs); it is posited that oxygenic photosynthesis by cyanobacteria in these microbialites provided a refuge from anoxic conditions (i.e., the "microbialite refuge" hypothesis). Here, we test this hypothesis by investigating the distribution of ~34, 500 benthic invertebrate fossils found in ~100 samples froma microbialite succession that developed following the latest Permian mass extinction event on the Great Bank of Guizhou (South China), representing microbial (stromatolites and thrombolites) and non-microbial facies. The stromatolites were the least taxonomically diverse facies, and the thrombolites also recorded significantly lower diversities when compared to the non-microbial facies. Based on the distribution and ornamentation of the bioclasts within the thrombolites and stromatolites, the bioclasts are inferred to have been transported and concentrated in the non-microbial fabrics, that is, cavities around the microbial framework. Therefore, many of the identified metazoans from the post-extinction microbialites are not observed to have been living within a microbial mat. Furthermore, the lifestyle of many of the taxa identified from the microbialites was not suited for, or even amenable to, life within a benthic microbial mat. The high diversity of oxygen-dependent metazoans in the non-microbial facies on the Great Bank of Guizhou, and inferences from geochemical records, suggests that the microbialites and benthic communities developed in oxygenated environments, which disproves that the microbes were the source of the oxygenation. Instead, we posit that microbialite successions represent a taphonomic window for exceptional preservation of the biota, similar to a Konzentrat-Lagerstätte, which has allowed for diverse fossil assemblages to be preserved during intervals of poor preservation.

Early Cretaceous vertebrate and invertebrate fossils from Dariyan Formation, southern Iran

ABSTRACT The Mesozoic fauna of southwestern Asia remains poorly understood. Here, we report on an assemblage of marine invertebrates and vertebrates from the Lower Cretaceous Dariyan Formation of Iran. The Dariyan Formation consists of 60 m of carbonates deposited in shallow seas. These deposits exhibit a high abundance of foraminifera that belong to nine genera and 14 species. Based on the succession of microfossil assemblages (Choffatella decipiens Range Zone, Radiolaria flood Range Zone, Globiogerinelloides blowi Range Zone, Mesorbitolina parva Range Zone), we propose that the Sivand fossiliferous deposits are Early Aptian (Bedoulian) through early Late Aptian (Early Gargasian) in age. Fossil vertebrates are preserved in the lower part of the formation. A diverse assemblage of fishes is present, including Aspidorhynchiformes, Ichthyodectiformes, Pycnodontiformes, Aulopiformes, and Clupeomorpha, and one genus of chelonioid turtle that is either a member of the Protostegidae or Dermochelyidae. The similarities in the fish assemblages of the Dariyan Formation of Iran with the Santana Formation of Brazil and the Tlayúa Quarry in south-central Mexico show that these fishes were distributed throughout the equatorial region and were widely spread in the shallow seaways of the Early Cretaceous.

Early Jurassic protobranch bivalves from Chubut, Argentina

AbstractKnowledge on Early Jurassic marine fossil invertebrates from Argentina is very uneven. Particularly, faunas from Chubut Province received less attention and were thought to be poorer than those from the Neuquén Basin. Nevertheless, an updated revision of bivalves shows that some groups, such as the Protobranchia, were relatively more diverse in Chubut than in Neuquén during late Pliensbachian–early Toarcian times. Only four species are known from the southern areas of the Neuquén Basin, while seven species (three of them new) are here described from Chubut, belonging to the families Nuculidae, Nuculanidae, Polidevciidae, and Malletiidae. The new species are:Palaeonucula feruglioin. sp.,Ryderia tehuelchanan. sp., andPhaenodesmia?piatnitzkyin. sp. The material is well preserved and allows a detailed analysis of their hinge regions and other internal characters. The presence in Chubut ofPalaeoneilo?patagonidica(Leanza) is confirmed, which, along withPraesaccella ovum(Sowerby), are the only two species in common with the Neuquén Basin. The new speciesRyderia tehuelchana, belonging to a genus that had a wide global distribution between Rhaetian and Toarcian times, but which was known from South America only for upper Triassic deposits, is of special paleobiogeographic interest. These bivalves are restricted to normal marine environments, and due to their detritivorous feeding habits they only live in organic-rich bottoms as very active shallow burrowers.UUID:http://zoobank.org/41225cf2-b7de-4ff0-ad20-ce0d738799a9

Ordovician strata in the Cliefden Caves area, New South Wales: a case study in the preservation of a globally significant paleontological site

The Cliefden Caves area in central-western New South Wales includes the scientifically most important and irreplaceable examples of fossiliferous Ordovician rocks in the State. Exposures of the stratigraphically lower parts of the Cliefden Caves Limestone Subgroup on the aptly named Fossil Hill are world-famous among paleontologists and internationally significant for preserving the earliest in situ shell beds documented in the literature. They also contain some of the oldest known rugose corals, and an exceptional example of one of the oldest coralline biostromes, as well as many examples of invertebrate fossils and cyanobacterial mat structures that either are unique to this locality or were first described from here. Other stratigraphic levels throughout the total 363 m-thick Cliefden Caves Limestone Subgroup are similarly endowed with highly significant fossils, such as a globally unique in situ shell bank with rare examples of the trimerellide brachiopod Belubula spectacula, a wealth of shelly fossils and trilobites on Dunhill Bluff (adjacent to Fossil Hill to the east), and the appropriately named Trilobite Hill. Less well known to the general public, but of international importance to paleontologists, is the unique deep-water sponge fauna of the overlying Malongulli Formation that occurs at several levels in limestone lenses within this unit. Fossils from the Cliefden Caves Limestone Subgroup and the Malongulli Formation have been documented in more than 60 scientific papers and monographs since paleontological investigations into the site were first published in 1895. Despite concerted scientific endeavour in the region over the past 50 years, much more study needs to be done to fully document the paleontological riches of the Cliefden Caves area. These sites are interpreted as the remains of a tropical island, fringed by limestone and flanked by deep-water environments in which the Malongulli Formation was deposited. Preservation of such islands is exceptionally rare in the geological record. It is therefore vital for the area to remain accessible to scientific researchers to continue their studies. Flooding of the Belubula Valley by a proposed dam downstream from the Cliefden Caves area would hinder future research work on this unique geoheritage resource. Fortunately, a successful public campaign has led to listing of the site on the State Heritage Register that will provide essential protection of the caves from inundation while ensuring continued access to researchers.

Mid Campanian‐Lower Maastrichtian magnetostratigraphy of the James Ross Basin, Antarctica: Chronostratigraphical implications

AbstractThe James Ross Basin, in the northern Antarctic Peninsula, exposes which is probably the world thickest and most complete Late Cretaceous sedimentary succession of southern high latitudes. Despite its very good exposures and varied and abundant fossil fauna, precise chronological determination of its infill is still lacking. We report results from a magnetostratigraphic study on shelfal sedimentary rocks of the Marambio Group, southeastern James Ross Basin, Antarctica. The succession studied covers a ~1,200 m‐thick stratigraphic interval within the Hamilton Point, Sanctuary Cliffs and Karlsen Cliffs Members of the Snow Hill Island Formation, the Haslum Crag Formation, and the lower López de Bertodano Formation. The basic chronological reference framework is given by ammonite assemblages, which indicate a Late Campanian – Early Maastrichtian age for the studied units. Magnetostratigraphic samples were obtained from five partial sections located on James Ross and Snow Hill islands, the results from which agree partially with this previous biostratigraphical framework. Seven geomagnetic polarity reversals are identified in this work, allowing to identify the Chron C32/C33 boundary in Ammonite Assemblage 8‐1, confirming the Late Campanian age of the Hamilton Point Member. However, the identification of the Chron C32/C31 boundary in Ammonite Assemblage 8‐2 assigns the base of the Sanctuary Cliffs Member to the early Maastrichtian, which differs from the Late Campanian age previously assigned by ammonite biostratigraphy. This magnetostratigraphy spans ~14 Ma of sedimentary succession and together with previous partial magnetostratigraphies on Early‐Mid Campanian and Middle Maastrichtian to Danian columns permits a complete and continuous record of the Late Cretaceous distal deposits of the James Ross Basin. This provides the required chronological resolution to solve the intra‐basin and global correlation problems of the Late Cretaceous in the Southern Hemisphere in general and in the Weddellian province in particular, given by endemism and diachronic extinctions on invertebrate fossils, including ammonites. The new chronostratigraphic scheme allowed us to calculate sediment accumulation rates for almost the entire Late Cretaceous infill of the distal James Ross Basin (the Marambio Group), showing a monotonous accumulation for more than 8 Myr during the upper Campanian and a dramatic increase during the early Maastrichtian, controlled by tectonic and/or eustatic causes.

Stratigraphic ranking of selected invertebrate fossils: A quantitative approach at different temporal and geographic scales

Stratigraphic ranking of selected invertebrate fossils: A quantitative approach at different temporal and geographic scales

Annotated Catalog of the Fossil Invertebrates Described by, and Named for,William More Gabb (1839-1878).

William More Gabb [1839-1878] described 1163 fossil invertebrate taxa: Protozoa [1 species], Porifera [1 genus, 2 species], Cnidaria [12 species], Bryozoa (with G.H. Horn) [1 family, 8 genera, 67 species], Brachiopoda [15 species], Annelida [7 species], Mollusca [Bivalvia: 15 genera, 2 subgenera, 412 species; Gastropoda: 1 family, 2 subfamilies, 42 genera, 8 subgenera, 489 species; Scaphopoda: 10 species; Cephalopoda: 1 family, 3 genera, 51 species], Arthropoda [Crustacea: 2 species; Cirripedia 1 species], and Echinodermata [11 species]. Listed herein are all fossil taxa named by Gabb, type localities, institutional depository, and remarks concerning current taxonomic status, when known. An annotated list of Gabb's fossil references is also included. Also listed herein are 134 fossil invertebrate taxa and 33 living mollusk taxa named for him.

First monodontid cetacean (Odontoceti, Delphinoidea) from the early Pliocene of the north‐western Pacific Ocean

AbstractMonodontids are among the most enigmatic cetaceans due to their scarcity in the fossil record. Previously, except for fragmentary materials, only three skulls were known from the pre‐Pleistocene; these came from the east coast of the Pacific and both east and west coasts of the Atlantic.Haborodelphis japonicus, a new early Pliocene monodontid cetacean from the north‐west Pacific, significantly expands the palaeobiogeographical extent of the ancestral monodontids. The new taxon differs from all other monodontids in the following character states: the robust postorbital process for the skull size; the short rostrum relative to the whole skull length; the anterior dorsal infraorbital foramina posterior to the level of the antorbital notch; the premaxillary foramen on the level of the antorbital notch; the dorsally gently convex premaxillary sac fossa; the palatines wedged into the maxillae anteriorly on the midline; and the presence of the clearly excavated posteromedial sulcus. Monodontids were almost certainly adapted to warmer waters than their living counterpartsDelphinapterus leucasandMonodon monoceros, both of which are confined to the high latitudes of the northern hemisphere. However, closer inspection (based mainly on fossil invertebrates) of the palaeoenvironments from which the monodontid fossils were produced, reveals that they may have preferred cooler conditions than previously thought. Due to the short climatic fluctuation cycles during the Pliocene in the northern hemisphere, and the increase of heterogeneity and regionality of the coastal environments, the dating of layers within a formation is critical for understanding palaeoenvironment in terms of the sea surface temperatures.

A micro X-ray computed tomography dataset of fossil echinoderms in an ancient obrution bed: a robust method for taphonomic and palaeoecologic analyses

BackgroundTaphonomic and palaeoecologic studies of obrution beds often employ conventional methods of investigation such as physical removal and extraction of fossils from their host rock (matrix) by mechanical preparation. This often-destructive method is not suitable for studying mold fossils, which are voids left in host rocks due to dissolution of the original organism in post-depositional processes.FindingsMicrocomputed tomography (µCT) scan data of 24 fossiliferous rock samples revealed thousands of Paleozoic echinoderms. Digitally "stitching" together individually µCT scanned rock samples within three-dimensional (3D) space allows for quantifiable taphonomic data on a fossil echinoderm-rich obrution deposit from the Devonian (Emsian) of South Africa. Here, we provide a brief step-by-step guide on creating, segmenting, and ultimately combining sections of richly fossiliferous beds to create virtual models suited for the quantitative and qualitative taphonomic analyses of fossil invertebrate assemblages.ConclusionsVisualizing the internal features of fossiliferous beds in 3D is an invaluable taphonomic tool for analyzing delicate fossils, accounting for all specimens irrespective of their preservation stages and with minimal damage. This technique is particularly useful for analyzing fossiliferous deposits with mold fossils that prove to be difficult to study with traditional methods, because the method relies on the large density contrast between the mold and host rock.