Fossil Microvertebrates

A B S T R A C T Very few excavated sequences in southern South America provide an approximation to the environmental evolution covering the segment Late Pleistocene-Holocene. Here we present the taphonomic analysis and pa-leoenvironmental reconstruction based on the small mammal remains retrieved from the archaeological and paleontological site Gruta del Indio (Mendoza Province, Argentina). Radiocarbon dates situate the small mammal deposits studied within the Late Pleistocene and Holocene. Thus, these assemblages provide a record for inferring environmental evolution in the middle basin of Atuel River during the last ∼31 ky BP. Taphonomic analysis revealed that most of small mammal remains were incorporated by a little destructive nocturnal owl. Recorded species include mainly cricetid and caviomorph rodents and a single marsupial. While Pleistocene assemblages have not exclusive species, the specific richness increases towards the Holocene probably linked with the climatic variability related to ENSO. In overall, the recorded small mammals suggest environmental stability during the Late Pleistocene-Holocene, mostly associated with Monte Desert conditions. Conversely, the pollen sequence studied from Gruta del Indio was interpreted as indicator of a deep environmental change during the Pleistocene-Holocene transition, when the Patagonian steppe was replaced by Monte Desert. Potential biases linked with these kinds of proxies are discussed.

The presence of microvertebrates in archaeological sites can be attributed to a variety of causes, including natural ones, such as the regurgitation of microvertebrates consumed by various predators. Determining the origin of these remains is therefore of great importance to our understanding of site formation processes. In addition, the detailed study of these remains can provide complementary data on such topics as the composition of biocenoses, palaeoenvironments and the seasonality of deposits. In this study, we analyzed modern sets of regurgitated pellets of the barn owl (Tyto alba) from the Alero Deodoro Roca site (ADR), Ongamira, Córdoba, Argentina. We compared the results with those from archaeological microvertebrates from excavations at ADR, dating to the Late Holocene (ca. 1900–3600 years BP). Most of the archaeological assemblages show the same composition as those of the modern pellets produced by Strigiformes. However, we observed variation in the representation of taxa, reflecting environmental changes over time. Using current temperature and humidity data to compare the assemblages, we observed that some results could be related to Holocenic climatic variations, already described by other studies. Furthermore, this research suggests that Strigiformes may occupy the rockshelters in Autumn-Winter, at which time the site (ADR) would not have been occupied so intensely by human populations.

The present study analyzes zooarchaeological and palaeoenvironmental trends from an assemblage of small mammals recovered from Agua de la Tinaja (AT), an archaeological site from an intermountain valley of the
Andean cordillera (northern Mendoza, Argentina). Small mammal remains recovered from AT, chronologically associated with 900–600 years BP, showed taphonomic traces corresponding to the action of owls and humans. Such results were included and compared within the framework of a resource intensification process suggested for Prehistoric human societies from northern Mendoza in Central Western Argentina. The small mammal assemblage from AT is composed by typical species from highland areas (Abrothrix andina, Microcavia australis, Phyllotis xanthopygus) mixed with some species from the Monte Desert (Calomys musculinus, Ctenomys sp., Eligmodontia sp., Thylamys pallidior) and Abrocoma sp. The co-occurrence of some species with modern allopatric distributions could support a scenario of greater environmental heterogeneity during the late Holocene than in
the present. A situation like this could be consistent with a more dense vegetation cover and larger availability of patch resources.

Background: To date, the Lower Cretaceous Jehol Group of western Liaoning, China has yielded five monotypic genera of anurans, including Liaobatrachus grabaui, Callobatrachus sanyanensis, Mesophryne beipiaoensis, Dalianbatrachus mengi, and Yizhoubatrachus macilentus. However, the validity and distinctness of these taxa have been questioned.

A B S T R A C T Paleopathology in bones of very small mammals has rarely been studied. Different types of osseous lesions of mammals weighing under 0.2 kg, recovered from the Holocene strata of Cueva Tixi archaeological and pa-leontological site (Tandilia range, province of Buenos Aires, Argentina), are described and discussed in this report. Several types of trauma, entheseal changes, degenerative joint diseases, and probable osteomyelitis were identified. The lesions were chronic, indicating that the animals were able to survive a period of convalescence, although in many cases the decreased capacity for locomotion likely was significant. These pathological findings open research avenues for very small mammals that usually are not considered in archaeological disease studies.

Prior to geochemical analyses, fossil bones and teeth are often extracted from any surrounding lithified sediments using chemical techniques such as immersion in acid. As stable isotope analysis becomes more commonplace in palaeoecological investigations, it is important to consider what effects these chemical preparation techniques may have on any subsequent isotopic data and to constrain these effects as quantitatively as possible. This study aims to elucidate these effects, as it is vital that variability in a data set should not be introduced as a result of protocols used during sample preparation; in addition, it defines the most effective and viable method of carbonate removal for processing bulk fossil samples without causing alteration of their stable isotopic signatures. Various strengths of two weak acids commonly used during palaeontological preparation were tested to evaluate their effects on the δ15N and δ13Corg isotopic signatures of the vertebrae of a large Eocene fossil fish. Changes in the isotopic values occurred over time regardless of which acid was used, each causing a variable response in both δ15N and δ13Corg isotopic values. Without careful monitoring of the acidification process in a controlled environment, any resulting data could therefore confound interpretation. Based on these experiments, it is recommended that 2 m acetic acid be used for the pretreatment of fossils prior to the acquisition of N and C isotope data where carbonate removal is necessary.

The late Middle Jurassic (Callovian) Peterborough Member of the Oxford Clay Formation of eastern England yields a rich variety of marine vertebrate fossils, including a diverse assemblage of neoselachian
elasmobranchs. Here we report the first record of the small Jurassic orectolobiform shark Akaimia Rees, 2010, otherwise known only from Poland and Germany, from the British Jurassic, together with an unusual, undetermined dermal denticle. The material comes from exposures in Cambridgeshire, eastern England. We refer the new specimens of Akaimia to the new taxon A. myriacuspis sp. nov., and provide a revised diagnosis for the genus.

Micromammalian bone assemblages from modern pellets of the strigiform Bubo virginianus magellanicus, from the upper Atuel River (southern Mendoza, Argentina), were taphonomically analysed. The results allow us to place B. v. magellanicus in the category of intermediate modification (Category 2). This sample has also been compared with results from other members of this genus, in order to classify B. v. magellanicus as a taphonomic agent. The participation of the Bubo species in archaeological accumulations has been documented , but in Argentina, the role of B. v. magellanicus has been reported up to the present. It is partly because of the sequence of one archaeological site in the south of Mendoza Province called Laguna El Sosneado-3 (LS-3). However, considering the absence of a current taphonomic model of this owl, this participation was mentioned as a hypothesis. In the current investigation, archaeological and modern samples have been compared. The results indicate that the skeletal element assemblages recovered from LS-3 were accumulated by strigiform birds. Taphonomical evidence of light modifications on units I and IV indicates that Tyto alba (Category 1) was probably the main species involved in these units, whereas the taphonomical evidence on skeletal element assemblages recovered from units II and III suggests the action of a strigiform with a major category of modification such as B. v. magellanicus.

Venom delivery systems occur in a wide range of
extant and fossil vertebrates and are primarily based on oral
adaptations. Teeth range from unmodified (Komodo dragons)
to highly specialized fangs similar to hypodermic needles
(protero- and solenoglyphous snakes). Developmental biologists
have documented evidence for an infolding pathway of
fang evolution, where the groove folds over to create the more
derived condition. However, the oldest known members of
venomous clades retain the same condition as their extant
relatives, resulting in no fossil evidence for the transition.
Based on a comparison of previously known specimens with
newly discovered teeth from North Carolina, we describe a
new species of the Late Triassic archosauriform Uatchitodon
and provide detailed analyses that provide evidence for both
venom conduction and document a complete structural series
from shallow grooves to fully enclosed tubular canals. While
known only from teeth, Uatchitodon is highly diagnostic in
possessing compound serrations and for having two venom
canals on each tooth in the dentition. Further, although not a
snake, Uatchitodon sheds light on the evolutionary trajectory
of venom delivery systems in amniotes and provide solid
evidence for venom conduction in archosaur-line diapsids.


Keywords Venom . Uatchitodon . Uatchitodon schneideri .
Evolutionary trajectory . Triassic

The actual abstract (summary) is 2 printed pages.

This monograph is based on my PhD dissertation and describes microvertebrate faunas from seven localities in the lower Chinle Group of Texas, New Mexico, and Arizona. This includes Trilophosaurus quarry 1 (Colorado City Formation, TX), the lower and upper Kalgary localities (Tecovas Formation, TX), the Ojo Huelos locality (Ojo Huelos, NM), L-2739 (Sixmile Canyon, NM), Krzyzanowski bonebed (St. Johns, AZ), and Dying Grounds (Petrified Forest, Arizona). There's a few new taxa here---Diplolonchidion murryi, Palaeollanosaurus fraseri, Planocephalosaurus lucasi, Crosbysaurus harrisae, and Protecovasaurus lucasi. They are a shark, two sphenodontians, and two archosauriforms that may or may not be convergent with early ornithischians or pterosaurs (subperpendicular, offset denticles). I particularly like Crosbysaurus because it has compound denticles and would appear to represent an intermediate stage between fine denticles (serrations) and coarse denticles typical of both Revueltosaurus and many ornithischian dinosaurs.

In this paper, the current state of knowledge of the taphonomic characteristics of micromammal (rodents and marsupials) remains
generated by the action of the different predators (avian raptors and carnivore mammals) of South America (particularly of Argentina), known
through actualistic studies, is reviewed. The analyzed taphonomic attributes enabled the adjustment, by means of extensive comparisons
among different groups of predators and prey, of the modification categories indicated in the original papers. The data herein revised and
assessed suggest that the evaluated South American predators may be grouped into four categories of modification: a) Light (Tyto alba, Bubo
virginianus, Strix chacoensis and Asio flammeus); b) Moderate (Athene cunicularia, Geranoaetus melanoleucus, Geranoaetus polyosoma and Pseudoscops
clamator); c) Heavy (Circus buffoni, Caracara plancus, Elanus leucurus, Didelphis albiventris, Leopardus geoffroyi and Lontra longicaudis); d) Extreme
(Milvago chimango, Puma concolor, Puma yagouaroundi, Conepatus chinga and Lycalopex griseus). Finally, the research herein discussed
evaluates how these studies were applied in the fossil record of both palaeontological and archaeological sites of South America.

Abstract—The Fruita Paleontological Research Natural Area (FPA) is remarkable for the abundance and diversity of
Upper Jurassic terrestrial fossils preserved within an area of approximately one square kilometer. Taking advantage of
the three-dimensional outcrop at the FPA, high-resolution event stratigraphic methodologies have been used to correlate
the crevasse splays (flood deposits) and to evaluate the interrelationships of individual fossil sites to each other and
to specific local environments. These include: (1) bank-controlled, gravelly, low-sinuosity river channels (ribbon
sandstones facies), (2) clay-dominated levees with well-sorted, sandstone, proximal crevasse-splay complexes best
developed at channel bends (levee facies), (3) drab, poorly-drained, alkaline flood plains with carbonate-cemented
crevasse splays and poorly-developed paleosols (drab flood-plain facies), (4) well-oxidized, well-drained flood plains
having well-developed paleosols with nodular carbonates (dark red flood-plain facies), (5) relatively permanent springfed
ponds or marshes locally overlying channel thalwegs (pond/marsh facies), and (6) ephemeral alkaline flood-plain
ponds characterized by barite nodules (alkaline pond facies). The distribution of active and abandoned channel-levee
complexes controlled depositional base level within the flood-plain environments. The facies defining these environments
also preserved distinctive suites of fossils: (1) ribbon sandstone facies preserve large dinosaurs, aquatic crocodilians,
turtles, unionid bivalves, and isolated logs, (2) levee facies preserve dinosaur bones and diverse trace fossils,
(3) drab flood-plain facies preserve evidence of dinosaur nests, diverse small terrestrial vertebrates, and diverse trace
fossils associated with crevasse splays, (4) dark red flood-plain facies do not preserve significant body fossils, but
preserve abundant root traces and other trace fossils, (5) pond/marsh facies preserve abundant carbonaceous plant
materials, logs, aquatic invertebrates, fish, and dinosaurs, and (6) alkaline pond facies preserve small delicate fossils
washed in from across the flood plain, including invertebrates, fish scales, and small terrestrial vertebrate fossils
(many with intact skeletons). The conceptual framework described herein forms a basis for further research on the
extraordinary natural laboratory preserved within the Morrison Formation at the FPA.

Owl predation is one of the most recurring causes of small mammal (˂1kg) accumulations in both archaeological and paleontological rock shelters, karstic system and open-air sites. The earliest actualistic taphonomic researches of small mammal remains have emerged in the 1970s and 1980s. However, it was not until the 1990s that a clear and analytical methodology was established, using small mammal species from North America, Europe and Africa. During the mid-to late 1990s actualistic taphonomic works began to be developed in South America, with exclusivity in Argentina and Chile. Since 21st century started to exponentially multiply the actualistic papers mostly of owls with a strict application of the taphonomic methodology. The useful of these studies in the archaeology (even paleontology) of South America also followed this growing tendency. However, since some years, it has been highlighting the disparity in the evidence of digestive action on different taxa. Thus, this methodology was recently re-evaluated considering the dentary morphology of rodents and marsupials from South America. The results achieved to date, added to what we intend to develop in the future will allow to obtain a higher level of detail and a better interpretation of the small mammal assemblages recovered from archaeological and paleontological sites of South America.

West Qinling is an important  area for the study of the Silurian/Devonian Boundary (SDB) in the South China Block. The SDB sequence in the Putonggou Section includes the upper part of the Yanglugou Formation and the lower part of the Xiaputonggou Formation, in which microvertebrate remains (thelodonts, placoderms, acanthodians and chondrichthyans) in association with conodonts and brachiopods have been collected. Two microvertebrate assemblages are recognized in the Putonggou Section: the Yanglugou Assemblage from the upper part of the Yanglugou Formation, and the Xiaputonggou Assemblage from the lower part of the Xiaputonggou Formation in association with the conodont Icriodus woschmidti woschmidti. The Yanglugou Assemblage yields the acanthodians Gomphonchus sandelensis and Ischnacanthidae gen. indet., and the Xiaputonggou Assemblage includes the thelodonts (Parathelodus scitulus, P. asiaticus and P. cornuformis), the acanthodians (Nostolepis gracilis, N. striata, N. tewonensis, Gansuichthys liui, Poracanthodes zoigenensis, Poracanthodes cf. P. porosus, Ischnacanthys sp.), the chondrichthyan (Arauzia ? sp.), and the placoderm (a pectoral ¿n fragment of Chuchinolepis ? sp.). Based on the correlation with the microvertebrate biozones in East Baltic, the Yanglugou and Xiaputonggou assemblages are referred to the Late Pridoli and the early Lochkovian respectively, thus providing paleoichthyological evidence for the location of the SDB in West Qinling.

Abstract. The fossil-bearing Maastrichtian continental deposits of the Haţeg Basin have been assigned to different lithostratigraphic units and subunits based on their lithology and fossil content; among these, the vertebrate fossil-and volcanoclast-bearing beds from the ...

La grotte du Lazaret a livré de nombreuses industries acheuléennes, plusieurs restes d'anténéanderthaliens et de très nombreux restes de vertébrés (amphibiens, reptiles, oiseaux et mammifères) reflétant une importante richesse spécifique. Les différentes associations fauniques, ainsi que le degré d'évolution de certaines espèces, permettent d'attribuer les dépôts archéologiques au Pléistocène moyen final (MIS 6), en accord avec les datations radiométriques. L'étude interdisciplinaire des ensembles stratigraphiques CIII et CII supérieur a permis de reconstituer le cadre paléoclimatique et paléoenvironnemental, et de mettre en évidence une certaine variété de paysages continentaux liés à un climat relativement froid, toutefois tempéré par la position méridionale du site. La présence d'espèces de climat froid actuellement disparues du biome méditerranéen implique l'existence de conditions plus fraîches et plus humides qu'aujourd'hui. Des fluctuations sont cependant perceptibles tout au long de la séquence au travers des variations de faunes, au niveau spécifique et quantitatif, montrant une relative intensification du froid et une ouverture progressive du milieu entre les ensembles CII sup. et CIII. Le spectre faunique de la grotte du Lazaret fournit un reflet assez juste de la paléobiodiversité dans le Sud-Est de la France à la fin du Pléistocène moyen (MIS6).

The Iron Springs Formation represents a braidplain consisting of sediments shed from the eastward advancing
Sevier orogenic belt, and the fauna it contains is the most proximal, relative to the orogenic belt, of those recovered
from the Cretaceous of southern Utah. The fauna spans the Cenomanian into Santonian (and possibly the early
Campanian). Among the taxa of fishes, the fauna includes four elasmobranch, one rhinobatoid, two neopterygian,
two teleost, and one dipnoan. The lissamphibians are quite diverse and include anurans (at least 1 taxon), urodeles
(at least 6 taxa), and albanerpetontids (at least 1 taxon). The squamates are of surprising low diversity, represented
by only three taxa. Theropod dinosaurs are present including two taxa of dromaeosaurs, two taxa of coelurosaurs,
and an unknown taxon. Among ornithiscians, an ankylosaur, an ornithopod, and possibly a ceratopsian are present.
Sixteen mammalian taxa including multituberculates, marsupials, a spalacotheriid, and a symmetrodont are present.
This is a relatively high diversity fauna from a small sample suggesting that the upland fauna was not greatly different
from those recovered from adjacent plateaus (Markagunt, Paunsaugunt, and Kaiparowits) to the east. The
diversity represented by this small sample suggests the potential for more extensive research in the Iron Springs
Formation.

The Upper Cretaceous (Maastrichtian) continental deposits of the HaŃeg Basin are well known for the diverse vertebrate assemblage they have yielded. Most of the taxa have been identified through intense micropaleontological processing of the material collected from across the basin.

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Known since the beginning of the 20th century for their abundant and diverse paleofloristic content, the Maastrichtian deposits of the Rusca Montană Basin yielded no vertebrate fossils until recently, when sauropod, ornithopod, theropod, chelonian, crocodylian and multituberculate remains have been discovered in floodplain fines and river channel sandstones cropping out in the eastern part of the basin. This paper presents additional fossils from a potentially new site within the same area, belonging to taxa and metataxa previously unknown in the Rusca Montană Basin. The fossil assemblage includes anurans, albanerpetontids, lizards, ziphodont crocodylians, additional small theropods, eggshells, freshwater gastropods and angiosperm fructifications. The faunal and sedimentological data suggest that the fossil assemblage is largely autochthonous, and thus reflects the composition of a wetland, poorly drained distal floodplain paleo-ecosystem.