Taphonomic Features Research Articles

Occurrence and Preservation of Gastropod Shells in Recent Riverine and Estuarine Sediments of Chennai, SE-India

Objectives: The distribution of aquatic gastropod shells was investigated in riverine and coastal sediments of Chennai, India. Next to taxonomic identification, the shell preservation was characterized and quantified with a taphonomic grade. Methods: Sediments of the Adyar and Cooum rivers as well as of coastal backwaters of the metropolitan area were taken down to a maximum depth of 81 cm using a handheld geoslicer and inspected by optical and electron microscopy. Taphonomic features (i.e. exfoliation, external luster, cracking, fragmentation, edge preservation, bioerosion, encrustation) reflecting different destructive post-mortem processes were observed, individually ranked and averaged in a composite taphonomic grade for each specimen. Results: Shells and shell fragments of various families occur with markedly different abundances between 63.7 and < 1% (in decreasing order Potamididae, Bithyniidae, Stenothyridae, Planorbidae, Thiaridae, Bullinidae, Nassariidae, Neritidae, Paludomidae). Their distribution invokes salinity as a major factor controlling occurrence in a habitat. The lack of larger and globose shells in freshwater river sediments may reflect the preference of stagnant water habitats and limited preservation in sedimentary transport. The predominance of Pirenella cingulata among the shells found in sediments of brackish environments probably reflects mechanical robustness and its extreme abundance in tidal flats. Due to post-mortem destruction most shells are incomplete. Roughly 25% of all specimens are almost complete shells not only showing spire and body whorl but at least in part also apex and/or aperture and outer lip. More than 50% represent spires or combinations of apex and spire. Composite taphonomic grades for gastropod families show a large range and reach high values. The lowest grades, indicative of best preservation, are observed for Stenothyra blanfordiana and Bithynia sp. Novelty: The distribution of gastropods in riverine and coastal environments represents a valuable ecosystem characteristic. Shell preservation shown here for sediments of Chennai is the basis for retrospective environmental characterization. Keywords: Gastropods; shells; river sediments; taphonomy; Chennai

High-resolution taphonomy and sequence stratigraphy of internally complex, bakevelliid-dominated coquinas from the Aptian Romualdo Formation, Araripe Basin, NE Brazil

The Aptian Romualdo Formation (Araripe Basin, NE Brazil) was deposited in a restricted epeiric sea, during the opening of the South Atlantic Ocean, with a coeval record to that in the Brazilian Pre-Salt succession. The upper part of the Romualdo Formation encompasses the Highstand Systems Tract of a third-order stratigraphic sequence, and contains shell beds interbedded with shale, siltstone, and fine-grained sandstone. Based on distinct taphonomic features (shell sorting, fragmentation, abrasion, rounding, and orientation), sedimentological criteria (shell abundance, type of matrix, sedimentary structures, and presence/absence of quartz grains), and stratigraphic attributes (bed thickness, geometry, contacts), the paleoenvironmental conditions and the bed-by-bed accumulation history of the coquinas is disentangled. Eight carbonate microfacies were recognized, including ostracod carbonate mudstone, bivalve-gastropod wackestone, gastropod-bivalve packstone, bivalve-gastropod grainstone, bivalve-gastropod floatstone, bivalve-gastropod rudstone, bakevelliid floatstone, and bakevelliid rudstone, which are organized in six, cm-thick shell concentrations. Mudstone and wackestone facies mark the settling of carbonate muds without significant bottom currents and wave action, probably below storm wave base, whereas packstone, floatstone, and rudstone, with fragmented, rounded, and oriented shells, were deposited in agitated waters, between the fair-weather and the storm wave bases. Ripple cross-laminated grainstone is interpreted as high-energy facies deposited above fair-weather wave base. The shell beds are internally complex and consist of cm-scale alternations of microfacies differing in packing, sorting, and composition. They tend to fine upwards within dm-thick shell beds, generating shallowing-upward facies sequences. The concentrations, the uppermost one with in situ bakevelliid shells in the top, record high-frequency base level oscillations influenced by eustasy and climate changes. These bioclastic accumulations originated by the superposition of sedimentologic and primary biologic processes (e.g., post-deposition meiofaunal bioturbation). The cm-thick, low-diversity shell beds are excellent examples of multiple-event carbonate deposits generated in a siliciclastic-dominated, restricted epeiric sea, revealing high-frequency cycles in proximal to distal restricted marine settings.

Bored log-grounds by teredinid bivalves in marine deposits from the Monos Formation (Upper Cretaceous) in central Cuba

Abstract Borings of Apectoichnus longissimus and Teredolites clavatus are described from wood fragments preserved in sandstone deposits of the Maastrichtian (Upper Cretaceous) Monos Formation in central Cuba. In addition, palaeobiological, palaeoecological and taphonomic implications of these are inferred. The borings are interpreted as mainly produced by Teredinid marine bivalves, which inhabited driftwood substrates. The taphonomic features such as mode of occurrence, density and position of the borings within the relict log-grounds suggest: (i) post-burial compaction of the xylic substrates by the surrounding sediments during burial, (ii) different ontogenetic stages and colonization episodes of teredinids on the studied wood fragments and (iii) different residence time of the wood fragments floating or near the sediment–water interface. Furthermore, the accumulation of wood fragments with A . longissimus and T . clavatus in the shallow marine deposits of the Monos Formation was probably the result of a marine transgression event in these deposits, thus leaving them exposed to attack by teredinid larvae. This study explores the life histories and taphonomic histories of teredinid bivalves and wood fragments in the Monos Formation, adding to the literature on ichnofossils in this lithostratigraphic unit.

A LATE MIOCENE MAMMAL ASSEMBLAGE REVEALS A COMPLEX TAPHONOMIC HISTORY IN FLUVIAL DEPOSITS OF CENTRAL ARGENTINA

ABSTRACT Micro- and macromammal remains from Cerro La Bota (late Miocene; La Pampa Province, Argentina) are taphonomically analysed. All remains form a single sample recovered from Chasicoan sediments (facies FA2) of the Cerro Azul Formation, constituted by a lateral and vertical erosive superposition of sandstone and conglomeratic bodies, formed by episodic development of perennial streams without flow division on a loessic substrate. The analysis reveals that micro- and macromammal remains originally accumulated independently and differently. Once each type of accumulation was buried in a loessic context, the development of streams gave place to a reworking process of fossils that were finally incorporated together into the stream channel. Taphonomic characteristics of micromammals are interpreted as the result of the leftover prey accumulated by predators, probably at a den site. Instead, the macromammals respond to an attritional accumulation of individuals inhabiting the area. Even considering the reworking as an important process that affected this assemblage, the taxonomic and taphonomic evidences suggest a relatively short time for its formation. The different taphonomic histories of the remains evidence a complex association that differs from other assemblages from the Cerro Azul Formation previously analysed, and it is here assigned to the channel-lag taphonomic mode.

Taphonomic bias in preservation and representativeness of skeletal samples (a case of Gonur Depe)

The topic of this article is theoretical and practical issues underlying the problems of representativeness of skeletal samples, as well as age and sex biases in preservation of skeletal remains, and the impact of these fac-tors on paleodemographic reconstructions. The impact of taphonomic bias in preservation on the qualitative and quantitative composition of skeletal sample is discussed on the materials from Gonur Depe — a Bronze Age proto-urban center in Southern Turkmenistan (2500–1500 BC, BMAC — Bactria-Margiana archaeological com-plex, also referred to as Oxus Civilization). The analyzed sample consists of skeletal remains of 500 individuals (215 non-adults, 115 adult males and 170 adult females) excavated between 2008 and 2015. Based on the type of preservation of skeletal remains, their completeness, as well as the preservation index (computed for each individual by dividing the number of long bones present by 14 — their maximum number per individual), three preservation classes were identified, of which class 1 corresponds to poor, and class 3 — to good state of preser-vation. Comparison of sex and age groups per each preservation class using сhi-square test demonstrates that in the Gonur Depe skeletal remains of infants (0–4 years old) and young adults (under 35 years of age) show the best state of preservation. Skeletons of elderly adults (over 35 years of age) have the worst state of preservation. There are no statistically significant differences between sexes in the degree of bone preservation. On the one hand, these results, contrary to theoretical expectations, testify against the existence of taphonomic biases in preservation of infant and female skeletons. On the other hand, the underrepresentation of elderly individuals in the studied collection is probably explained by a decrease in resistance to taphonomic processes due to the ac-celerated loss of bone calcium. It has been concluded that age and sex-related biases in the demographic struc-ture of prehistoric skeletal samples cannot be universally explained by the preservation factor. Misrepresentation in the percentage of different age and sex groups is a non-linear and a complicated process that requires consid-eration of different factors affecting the qualitative and quantitative composition of a particular skeletal sample. A detailed assessment of the taphonomic characteristics of a studied skeletal collection should be a mandatory step prior to its analysis by paleodemographic methods.

Taphonomic-forensic analysis of the hominin skulls from the Sima de los Huesos.

The Sima de los Huesos (SH) hominin assemblage is composed of thousands of fossil fragments, including pieces of crania and mandibles. The main objective of this work is to address the main taphonomic features of the cranial and mandibular remains from the SH sample, including antemortem, perimortem, and postmortem skeletal disturbances. We present an updated assessment of healed cranial trauma, first described in 1997 and now including new skulls. In addition, this study reviews the perimortem fractures in relation to their location and features of the affected individuals. Finally, this paper deals with the modifications affecting the cranial sample from the SH at the postmortem stage, including physical and biological postdepositional modifications. The SH collection provides a unique opportunity for conducting a complete forensic-taphonomic study on a Middle Pleistocene population.

PALAEONTOLOGY OF THE UPPER PLIOCENE MARINE DEPOSITS OF RIO VACCARUZZA, VILLALVERNIA (PIEDMONT, NW ITALY)

Abstract. The topmost Argille Azzurre (beds 1-2) and the basal Sabbie di Asti (beds 3-9) formations in the Villalvernia area are analysed in terms of palaeoecological and taxonomic features; the succession is 6 m thick and dates back to the middle Piacenzian within the Globorotalia bononiensis acme. The upper boundary of the clayey Bed 2 corresponds to an unconformity reflecting Pliocene tectonic activity. The study is focused on the fossil assemblages of beds 3, 4 and 9. The sandy Bed 3 yields 362 mollusc taxa; their assemblage is allochthonous and mixes infra- to circalittoral species accumulated by hyperpycnal mass-transport. The same mechanism is responsible for the origin of the overlying fossil unit (Bed 4) with numerous specimens of the Entobia-Gastrochaenolites ichnofacies. The autochthonous fossil assemblage of Bed 9 yields 308 molluscs, plus three brachiopods and ten fish taxa; most of them refer to the Posidonia meadow (HP), and their autochthony is shown by taphonomic features as skeletal integrity, mixing of successive generations or the limitation to juvenile ontogenetic stages of vagile and temporarily byssate species for which the HP performs a nursery function. Three brachiopods and 52 molluscs are here reported for the first time from the Pliocene of Piedmont. In the final chapter “Systematic Palaeontology” four brachiopods and 29 molluscs are described, among which there are eight new gastropod species: Crepidula bellardii n. sp., Conus dellabellai n. sp., Conus villalvernensis n. sp., Odetta chirlii n. sp., Ondina curta n. sp., Ondina elongata n. sp., Ondina pseudovitrea n. sp., Anisocycla subcylindrica n. sp.

A deep-sea foraminiferal assemblage scattered through the late Cenozoic of Antarctic Peninsula and its biostratigraphic and biogeographic implications

AbstractOur knowledge of the foraminiferal fossil record of Antarctica is notoriously patchy but still offers us an overview of its Cenozoic faunas. Few occurrences have been reported for the continent, with deep-sea assemblages described mainly for its eastern portion. Here we describe 21 taxa of large agglutinated foraminifers from the Miocene Hobbs Glacier Formation and the Plio-Pleistocene Weddell Sea Formation on Seymour Island, West Antarctica, including the gigantic Ammodiscus vastus new species. Most of them consist of genera or species typical of deep-sea agglutinated assemblages. All specimens are completely filled and partially covered by lithified micrite. This, along with the postfill fragmentation of some tests, indicates their re-elaboration from older deposits. Because all of these foraminifers share the same taphonomic features and most of them represent taxa associated with deep-sea settings, they probably represent a flysch-type assemblage from an unknown deposit that was eroded and had its microfossils scattered through post-Paleogene sediments. A Paleocene age for this putative assemblage is indicated by the presence of Reticulophragmiun garcilassoi (Frizzell, 1943), a Paleocene index fossil, and by its association with the Cretaceous–Paleocene Ammodiscus pennyi Cushman and Jarvis, 1928. If taken as a coherent foraminiferal assemblage, it represents one of the few deep-sea assemblages known for West Antarctica, and the first flysch-type assemblage recognized for the Antarctic Cenozoic. In addition, it would show that the Paleocene foraminiferal communities of the West Antarctica's deep-sea floor were more like their Pacific counterparts than their Atlantic equivalents.UUID: http://zoobank.org/0d281489-c0c6-47b4-9884-f820806485b7

D\xe9j\xe0 vu: a reappraisal of the taphonomy of quarry VM4 of the Early Pleistocene site of Venta Micena (Baza Basin, SE Spain)

Venta Micena, an Early Pleistocene site of the Baza Basin (SE Spain), preserves a rich and diverse assemblage of large mammals. VM3, the main excavation quarry of the site, has been interpreted as a den of the giant hyaena Pachycrocuta brevirostris in the plain that surrounded the Baza palaeolake. Taphonomic analysis of VM3 has shown that the hyaenas scavenged the prey previously hunted by the hypercarnivores, transported their remains to the communal den, and consumed the skeletal parts according to their marrow contents and mineral density. In a recent paper (Luzón et al. in Sci Rep 11:13977, https://doi.org/10.1038/s41598-021-93261-1, 2021), a small sample of remains unearthed from VM4, an excavation quarry ~ 350 m distant from VM3, is analysed. The authors indicate several differences in the taphonomic features of this assemblage with VM3, and even suggest that a different carnivore could have been the agent involved in the bone accumulation process. Here, we make a comparative analysis of both quarries and analyse more skeletal remains from VM4. Our results indicate that the assemblages are broadly similar in composition, except for slight differences in the frequency of megaherbivores, carnivores and equids according to NISP values (but not to MNI counts), the degree of bone weathering, and the intensity of bone processing by the hyaenas. Given that VM4 and VM3 were not coeval denning areas of P. brevirostris, these differences suggest that during the years when the skeletal remains were accumulated by the hyaenas at VM3, the rise of the water table of the Baza palaeolake that capped with limestone the bones was delayed compared to VM4, which resulted in their more in-depth consumption by the hyaenas.

New charcoal evidence at the onset of MIS 4: First insights into fuel management and the local landscape at De Nadale cave (northeastern Italy)

Archaeological evidence of Middle Palaeolithic sites in Europe dating to MIS 4 remains very scarce compared to those belonging to previous (MIS 5) and later (MIS 3) periods. Of the few documented, a very low number have provided anthracological data reflecting the local landscape and fuel gathering strategies during MIS 4 Neanderthal occupations. This factor especially limits our knowledge of local landscape dynamics and the climatic conditions where these human occupations occurred. In this paper we contribute to this context through charcoal data from De Nadale cave, a single-layered Mousterian site located in northeastern Italy (Berici Hills area) and dated to 70.2 + 1/−0.9 ka BP. Anthracological data suggests the preferential use of spruce / larch (Picea - Larix) as firewood together with cryophilous pines (Pinus tp. sylvestris) and birch (Betula sp.) indicating prevailing harsh climatic conditions. Additional analysis focused on taphonomic features affecting charcoal point out to advance decay evidence prior to charring caused by fungi and insects. Although further data is needed, our results provide complementary information agreeing with the faunal spectrum, the small mammals assemblage and the nearby terrestrial pollen sequences

New insights into the enigmatic Cretaceous family Spathiopterygidae (Hymenoptera: Diaprioidea)

The Cretaceous family Spathiopterygidae (Hymenoptera: Diaprioidea), containing five species in four genera, showed a wide distribution from the upper Barremian to the Turonian. We describe two new representatives of the family from the upper Albian San Just outcrop in the eastern Iberian Peninsula that correspond to Diameneura marveni gen. et sp. nov. Santer and Álvarez-Parra and to a female member of Mymaropsis turolensis Engel and Ortega-Blanco, 2013. The forewing venation of Diameneura marveni gen. et sp. nov. is interpreted, allowing an appropriate comparison for future descriptions. Furthermore, we provide a diagnosis for Mymaropsis baabdaensis since no diagnosis was proposed in the initial paper. We indicate the taphonomic characteristics of the newly described specimens, discuss the interrelationships of the family, and provide new insights about the sexual dimorphism and palaeobiology of spathiopterygids.

Taphonomic analysis of fossil concentrations from the Monte León Formation (lower Miocene), Santa Cruz Province, Argentina

The Monte León Formation (lower Miocene) carries many invertebrate fossil concentrations characterized by the abundance of well-preserved macro- and micro-mollusks which have been the object of systematic studies, but little information exists about its genesis. The aim of this work was to describe and analyse four fossil concentrations of this unit, exposed in the Cabeza de León section, in order to reconstruct the taphonomic history of the included bioclasts and identify the environmental conditions and the depositional processes involved in their origin. Sedimentological characteristics of the concentrations allowed, in addition to field observations, the collection of washable samples that were processed and analysed in the lab. Study of the palaeontological characteristics of these samples increased by over 150% the number of taxa and allowed the recognition of three polytypic concentrations with mixed size spectra, and one paucitypic concentration revealing a dominance of adults, suggesting the influence of diagenetic processes. The sedimentological and stratigraphic characteristics of the fossil concentrations suggest a low-to moderate-energy shallow marine environment, with interspersed hydraulic events favouring sediment input, tractive reworking and amalgamation. Taphonomic features suggest that bioclasts experimented different histories of burial, exposure, and reworking that favoured temporal and within-habitat time averaging. Final burial was product of storm events that favoured the preservation of aragonite shells and the mixing of infaunal and epifaunal shells with other transported shells from shallower environments.

TAFONOMÍA DE UNA CONCENTRACIÓN DE VALVAS DEL BIVALVO INVASOR Corbicula fluminea (MÜLLER, 1774), RÍO DE LA PLATA SUPERIOR, URUGUAY

The bioinvader bivalve Corbicula fluminea (Müller, 1774) is known in the Río de la Plata River since about 35 years ago. This time lapse fills a gap in taphonomical studies, that comprises usually strictly contemporaneous or at best centuries-old phenomena. We sampled shells of this species in one locality in two occasions with the same methodology. Fragmentation, presence of periostracum, corrasion, bioerosion and bioencrustation were studied externally in four sectors of the valve: umbonal, anterior, central, and posterior. We tested the differences in the frequencies of the attributes between the two samples by means of Χ2, resulting only significantly different corrasion in the umbonal sector and fragmentation in the central and posterior areas.The umbonal area was the most affected sector, and it was attributed to a higher exposition to corrasive agents (i.e., moving clasts) compared to other areas of the valve. Neither bioerosion nor bioencrustation was recorded, being this attributed to the less prevalence of these taphonomic features in the low salinity conditions of the study area.

Dinosaur bonebed amber from an original swamp forest soil.

Dinosaur bonebeds with amber content, yet scarce, offer a superior wealth and quality of data on ancient terrestrial ecosystems. However, the preserved palaeodiversity and/or taphonomic characteristics of these exceptional localities had hitherto limited their palaeobiological potential. Here, we describe the amber from the Lower Cretaceous dinosaur bonebed of Ariño (Teruel, Spain) using a multidisciplinary approach. Amber is found in both a root layer with amber strictly in situ and a litter layer mainly composed of aerial pieces unusually rich in bioinclusions, encompassing 11 insect orders, arachnids, and a few plant and vertebrate remains, including a feather. Additional palaeontological data-charophytes, palynomorphs, ostracods- are provided. Ariño arguably represents the most prolific and palaeobiologically diverse locality in which fossiliferous amber and a dinosaur bonebed have been found in association, and the only one known where the vast majority of the palaeontological assemblage suffered no or low-grade pre-burial transport. This has unlocked unprecedentedly complete and reliable palaeoecological data out of two complementary windows of preservation-the bonebed and the amber-from the same site.

Mesosaur taxonomy reappraisal: are Stereosternum and Brazilosaurus valid taxa?

Mesosaurs are basal amniotes that lived at the beginning of the Permian or close to the Permo–Carboniferous boundary. Despite the several hundred specimens that have been found, including complete skeletons of adult and juvenile individuals, mesosaur taxonomy has been subjected to a high controversy over time. Currently, three monotypic genera, Mesosaurus tenuidens Gervais, Stereosternum tumidum Cope, and Brazilosaurus sanpauloensis Shikama &amp; Ozaki are recognized, but identification of new specimens using the available diagnostic characters are arbitrary and influenced by high subjectivity. We performed anatomical and morphometric analyses to look for statistical support to these previously suggested basic diagnostic characters through an exhaustive anatomical revision of these characters and also of some new attributes discovered during the course of our study. We found a notable influence of taphonomic features in most of the diagnostic characters used to differentiate the three monotypic genera, including strong bias derived from the preservation of individuals in different ontogenetic stages, whose size and degree of ossification could have been controlled by particular environmental conditions that resulted in subtle polymorphisms of these and other few characters. Other features may even represent sexual dimorphism. After the detailed revision of the type specimens of the three currently accepted mesosaur taxa, for which we include here good-quality photographs, and considering the lack of statistical support for the most applied putative diagnostic features such as the different ratio found when comparing skull and cervical region lengths and the low or higher intensity of pachyosteosclerosis observed in dorsal ribs, which can be controlled by taphonomic and ecological conditions, we recognize Mesosaurus as the only mesosaurid taxon in the Paraná and Karoo basins, probably including dwarf individuals. Therefore, S.tumidum and B. sanpauloensis are suggested here as nomina dubia taking into account that the autapomorphies that supported these taxa cannot be confirmed to be absent in Mesosaurus. Keywords: Mesosaurus, morphometrics, taxonomy, ?Early Permian, Gondwana.

Pleistocene coralline algal buildups on a mid-ocean rocky shore – Insights into the MIS 5e record of the Azores

Located on the northern coast of Santa Maria Island (Azores Archipelago, central North Atlantic), the Lagoinhas section preserves a carbonate buildup correlated with Marine Isotope Substage (MIS) 5e, the warmest interval of the Last Interglacial. The buildup is formed mainly by crustose coralline algae (CCA) identified as Spongites sp., and some subordinate crusts of Lithophyllum sp. and Neogoniolithon sp., as well as cf. Titanoderma sp. Extant CCA buildups are not recorded in the archipelago. Herein, we describe in detail the morphological and taphonomical features of the Lagoinhas CCA buildup and interpret the environment in which it grew. Additionally, this buildup is compared with another of similar age, exposed in the Prainha-Praia do Calhau section on the island's opposite southern coast. The hydrodynamic regime appears to play a crucial role in the development of Azorean CCA buildups during the MIS 5e.

Mammal‐bearing gastric pellets potentially attributable to Troodonformosus at the Cretaceous Egg Mountain locality, Two Medicine Formation, Montana, USA

AbstractFossil gastric pellets (regurgitalites) have distinct taphonomic characteristics that facilitate inferences of behavioural ecology in deep time, despite their rarity in the fossil record. Using the taphonomic patterns of both extant and fossil small mammals from more recent geologic deposits as a guide, we assess the taphonomy of three unusual multi‐individual aggregates of mammal skeletons from palaeosols at Egg Mountain, a dinosaur nesting locality from the Upper Cretaceous Two Medicine Formation, Montana, USA. One aggregate consists of two individuals of the multituberculate Filikomys primaevus. This specimen is characterized by brecciated crania, articulated postcrania, and an absence of digestive markings, all suggestive of a non‐predatory origin. Two additional aggregates consist of 3 and 11 individuals, respectively, primarily of the marsupialiform Alphadon halleyi. High proportions of crania and indigestible elements (e.g. teeth), extensive disarticulation and breakage, digestive corrosion patterns, and the absence of a phosphatic ground mass are indicative of regurgitalites and align with features of extant prey in diurnal raptor gastric pellets. We interpret these specimens as the oldest known mammal‐bearing regurgitalites. The discrepancy in taphonomic features implies behavioural separation between the two mammalian taxa at the locality. Abundant shed teeth and nesting evidence at the locality favours the non‐avian theropod Troodon formosus as the predator responsible for the regurgitalites, congruent with previous inferences of a small‐bodied prey diet, manipulation of prey during feeding, heightened metabolic processes, and potential nocturnality for this taxon.

Kimmeridgian and early Tithonian cephalopods from the Kisújbánya Limestone Formation, Zengővárkony (Mecsek Mountains, southern Hungary), their faunal composition, palaeobiogeographic affinities, and taphonomic character

A new collection at Zengővárkony (Mecsek Mountains, Hungary) provided a rich and diverse but poorly preserved cephalopod-dominated fossil assemblage representing the Kimmeridgian and the lower Tithonian. The material came from mixed scree, soil, and amongst roots affected by weathering processes having been exposed to the elements for a long time. The nautiloid Pseudaganides strambergensis is the first record from the Mecsek Mountains. Due to the weathering, the ammonite fauna consists of mainly fragmentary and dissolved individuals that comprises 528 specimens belonging to 34 species and 30 genera out of which 20 species and 15 genera are reported for the first time from the Mecsek Mountains. The fauna includes specimens of known taxa. No new taxa are introduced. Based on the comparison with other faunas, this assemblage most closely resembles the fauna of the Venetian Alps (Italy). Additional faunal elements include aptychi (Laevaptychus latus, Lamellaptychus murocostatus), belemnites (Hibolithes semisulcatus), and an indetermined brachiopod. The first record of Spiraserpula spirolinites, an encrusting fossil polychaete preserved on the internal mould of a Taramelliceras shell fragment indicates favourable bottom conditions for the epifauna. The presence of Aspidoceras caletanum, Gravesia aff. gigas, and Pseudowaagenia inerme indicates faunal connections with the Submediterranean Province of the Tethys, which is in line with the tectonic and palaeogeographical position of the Mecsek Zone during the Late Jurassic. The ammonite assemblage represents elements of five Tethysian ammonite zones of the Kimmeridgian and Tithonian. The lower Kimmeridgian Herbichi Zone is indicated by Streblites tenuilobatus and Praesimoceras herbichi. The upper Kimmeridgian Acanthicum Zone is indicated by Aspidoceras acanthicum, and the Cavouri Zone by Mesosimoceras cavouri and Aspidoceras caletanum. The upper Kimmeridgian Beckeri Zone is suggested by Hybonoticeras pressulum and Pseudowaagenia inerme. Whereas Gravesia aff. gigas, Lithacoceras aff. siliceum, and Malagasites? denseplicatus are faunal elements characterising the Early Tithonian Hybonotum Zone. Phylloceratid and lytoceratid specimens account only for 12% of the fauna, while the majority of the specimens belong to the Oppeliidae and Ataxioceratidae (60%).

Taxonomy, biostratigraphic and paleoecological aspects of non-marine ostracod fauna from the Jinju Formation (Albian) of the Gyeongsang Basin, South Korea

A total of seven species belonging to six genera of cypridoidean ostracods were recovered from three sections (Jeongchon, Hotan, and Tapri) of the Albian Jinju Formation from the Gyeongsang Basin, South Korea: Scabriculocypris yanbianensis, Cypridea khandae sp. nov., Cypridea samesi, Mongolocypris kohi, Lycopterocypris? cf. celsa, Candona sp., and Djungarica sp. Based on its morphology, C. khandae sp. nov. is considered to be the first record of the Cypridea alta-group in Korea. Although many species are endemic to the Jinju Formation, the occurrence of Scabriculocypris yanbianensis indicates that this fauna was linked with the contemporaneous fauna of the Tongfosi Formation of the Yanji Basin, northeast China. Based on previous studies and newly collected specimens, the taphonomic features of the sections indicate the presence of two distinct thanatocoenoses: a low-energy autochthonous thanatocoenosis (Jeongchon and Tapri sections) and a slightly higher energy thanatocoenosis (Hotan section). Finally, the absence of cytheroidean and darwinuloidean ostracods could be explained by the presence of unstable lake/temporal waterbodies and their low competitiveness.

TAPHONOMIC ANALYSIS OF THE PALEOENTOMOFAUNA ASSEMBLAGE FROM THE CENOZOIC OF THE FONSECA BASIN, SOUTHEASTERN BRAZIL

ABSTRACT The Fonseca Formation (Eocene–Oligocene boundary, Minas Gerais, Brazil) is well known for its paleoflora, especially of flowering plants. The richness of this insect-bearing fossil locality is significantly less well understood, but we can shed light on the insect paleocommunity. One hundred and eight fossil insect specimens were examined and separated into four grades based on their preservational quality. We conducted analyses of taphonomic features, including body orientation, size, articulation, and chemical composition. Our results reveal differences in the body articulation of the insects. The fully articulated specimens apparently did not experience extensive flotation time at the water-air interface, whereas for partially articulated and disarticulated specimens the opposite is true. These taphonomic features would be acquired during the biostratinomy stage, and not early diagenesis. We also employed high resolution techniques (SEM-EDS and Raman spectroscopy) to understand their fossilization potential. Our chemical data suggest that the Fonseca insects are preserved as organic remains in carbonaceous compressions. Thus, chitin biomolecules most likely were transformed into more resistant biopolymers during diagenesis. This interpretation may also imply that the carbonaceous material originated from the insect itself. In this study, we document new discoveries and also provide future prospects for study of the Fonseca Formation.