The Stegodon Bonebed of the Middle Pleistocene Archaeological Site Mata Menge (Flores, Indonesia): Taphonomic Agents in Site Formation

The Middle Pleistocene fluvial channel site of the Upper Fossil-bearing Interval at Mata Menge in the So’a Basin, Flores, Indonesia, has yielded the earliest fossil evidence for Homo floresiensis in association with stone artefacts and fossils of highly endemic insular fauna, including Stegodon, giant rats, crocodiles, Komodo dragons, and various birds. A preliminary taphonomic review of the fossil material here aimed to provide additional context for the hominin remains in this bonebed. Analysis was performed on two subsets of material from the same fluvial sandstone layer. Subset 1 comprised all material from two adjacent one-metre square quadrants (n = 91), and Subset 2 all Stegodon long limb bones excavated from the same layer (n = 17). Key analytical parameters included species and skeletal element identification; fossil size measurements and fragmentation; weathering stages; bone fracture characteristics; and other biological and geological bone surface modifications. Analysis of Subset 1 material identified a highly fragmented assemblage with a significant bias towards Stegodon. A large portion of these bones were likely fractured by trampling prior to entering the fluvial channel and were transported away from the death-site, undergoing surface modification causing rounding. Subset 2 material was less likely to have been transported far based on its limited susceptibility to fluvial transport. There was no significant difference in weathering for the long limb bones and fragments, with the highest portion exhibiting Stage 2 weathering, indicating that prior to final burial, all material was exposed to prolonged periods of surface exposure. Approximately 10% of all material have characteristics of fracturing on fresh bone, contributing to the taphonomic context for this bonebed; however insufficient evidence was found for anthropogenic modification.

Introduced and native vertebrates in pink-footed shearwater (Ardenna creatopus) breeding colonies in Chile

Biodiversity conservation planning requires accurate, current information about species status and threats. Although introduced mammals are the greatest threat to seabirds globally, data on introduced species is lacking for many seabird breeding islands. To inform conservation planning, we used trail cameras to document the presence, relative abundance, and seasonal and diel attendance of introduced and native vertebrates within pink-footed shearwater (Ardenna creatopus) breeding colonies on Isla Mocha (five colonies, 2015–2020) and Isla Robinson Crusoe (Juan Fernández Archipelago), Chile (one colony, 2019–2020). The most commonly detected species were pink-footed shearwaters and introduced rats (Rattus spp.) on Isla Mocha, and European rabbits (Oryctolagus cuniculus) and pink-footed shearwaters on Isla Robinson Crusoe. Introduced mammals observed, in order of greatest catch-per-unit-effort, were rats, cats (Felis catus), dogs (Canis lupus familiaris), and European hares (Lepus europaeus) on Isla Mocha and European rabbits, cats, cattle (Bos taurus), rats, dogs, mice (Mus musculus), and southern coati (Nasua nasua) on Isla Robinson Crusoe. Especially noteworthy results for pink-footed shearwater conservation were the presence of cats during all monitoring months in shearwater colonies on both islands, that catch-per-unit-effort of rabbits was greater than shearwaters on Isla Robinson Crusoe, and that rats were the most observed vertebrates after shearwaters on Isla Mocha. Pink-footed shearwaters were regularly present on the islands from October through May. Presence and relative catch-per-unit-effort of pink-footed shearwaters qualitatively matched the species’ known breeding phenology. The regular presence and temporal overlap with shearwaters of cats, rats, rabbits, and cattle within shearwater colonies, coupled with the irregular presence of dogs, coati, hares, and mice, indicated a serious conservation threat for pink-footed shearwaters and other native insular fauna and flora. Finally, our study provides a widely applicable model for analysis of multi-year trail camera data collected with unstandardized settings.

Using a blind test to assess the discriminant power of morphological traits to distinguish between similar shrew species

The Canary Islands are home to a large variety of endemic fauna. The Canary shrew (Crocidura canariensis) has a distribution restricted to Fuerteventura, Lanzarote and the islets of Lobos and Montaña Clara. One of the main threats to the insular fauna is the arrival of exotic species. The greater white-toothed shrew (Crocidura russula) is an easily transportable animal and a potential competitor for C. canariensis. Therefore, C. russula should be taken into account in the management protocols for invasive species. One of the most easily applicable techniques for detecting shrews is the analysis of pellets. This study aims to assess which morphological characters are diagnostic and easy to use when identifying both species of shrews. For this purpose, a blind specific assignment has been made using seven previously described characters and another three added in the present study. The results show that the observer’s experience did not improve the correct identification rate and that only three of the evaluated characters have a high discriminant capacity. Finally, it was found that the combined use of the maximum number of characters and the identification by two independent observers reduces the probability of making a mistake in the determination to minimum values.

Axiidean ghost shrimps (Decapoda: Axiidae, Callianassidae, Callichiridae, Micheleidae) of the Trindade and Martin Vaz Archipelago, Vitória-Trindade Seamounts Chain and Abrolhos, off southeastern Brazil

The Trindade and Martin Vaz (TMV) volcanic archipelago is highly isolated, being located some 1200 km off the Brazilian coast and about 4200 km away from the nearest African coast. The only axiidean known from the archipelago is Coralaxius nodulosus (Meinert, 1877), a species extensively reported in the western Atlantic. From 2012 to 2018, 263 SCUBA diving and intertidal samplings were conducted at TMV and yielded 46 axiidean specimens in three species, one of which is a new species: Corallianassa longiventris (A. Milne-Edwards, 1870), Neocallichirus grandimana (Gibbes, 1850), and Fragillianassa joeli sp. nov., a species closely related to F. fragilis (Biffar, 1970). Hitherto unreported specimens from along the Vitória-Trindade Seamounts Chain (VTSC) and the Abrolhos Bank were also included in this report, namely C. nodulosus and Michelea vandoverae (Gore, 1987). The occurrence of M. vandoverae at the Abrolhos Bank extends its range into the southwestern Atlantic. Coralaxius abelei Kensley & Gore, 1981 is herein considered a junior synonym of Coralaxius nodulosus (Meinert, 1877). Meinertaxius Sakai, 2011, therefore becomes a subjective synonym of Coralaxius Kensley & Gore, 1981. Axiideans from the tropical southern-central Atlantic oceanic islands (Ascension, Fernando de Noronha, Rocas Atoll, Saint Helena, Trindade and Martin Vaz) are listed with their gross distribution in the Atlantic Ocean revealing a strongly depauperate axiidean insular fauna, totaling six species. Except for Axiopsis serratifrons (A. Milne-Edwards, 1873), a pantropical species, the insular southwestern-central Atlantic axiideans are entirely of western Atlantic affinities, with F. joeli sp. nov. being the only endemic so far.

The head skeleton of the Rhaetian sphenodontid Diphydontosaurus avonis gen. et sp.nov. and the modernizing of a living fossil

The skull and lower jaw of a new sphenodontid reptile Diphydontosaurus avonis is described from disarticulated bones. The fossils were recovered from a detrital limestone of Rhaetian age deposited within solutional and tectonically formed fissures within the Carboniferous Limestone of Tytherington quarry near Bristol. The bone remains, numbering over 1000, are exquisitely preserved with intact facets. Diphydontosaurus was the smallest member of an insular fauna, was primarily insectivorous, and probably formed locally high-density populations. Uniquely for a sphenodontid, Diphydontosaurus had pleurodont teeth on the premaxilla and on the anterior regions of the dentary and maxilla. However, Diphydontosaurus also has the series of acrodont teeth alternating in size on the maxilla and dentary which is characteristic of the Sphenodontidae and particularly Sphenodon . An analysis of 49 synapomorphs in the Diapsida emphasises the sphenodontid nature of Diphydontosaurus . A study of these synapomorphs among the other Triassic sphenodontids Clevosaurus and Planocephalosaurus and the eosuchian Gephyrosaurus suggests that the lack of a quadrate-quadratojugal conch and the complete lower temporal bar are secondarily derived in the ‘living fossil’ Sphenodon punctatus . The tuatara is therefore much less archaic than hitherto proposed. Functional reasons are advocated for the loss of the conch and the regrowth of a complete lower temporal bar. Transformation series are described which could have led to the shape of the maxilla, dentary, premaxilla, palatine and to the loss of the lacrimal in Sphenodon .