u/ReturntoPleistocene

Abstract

The jaguar ( Panthera onca ) is an adaptable, solitary predator that used to range from Argentina to the southwestern United States. Despite having been extirpated in several areas due to anthropogenic activities, there is a breeding population in the State of Sonora, and resident adults in Arizona, in the United States. Even though the State of Chihuahua is in close proximity and there is a likelihood of dispersal, there are no formal studies for the species in the State. As part of a broader monitoring project, we surveyed two privately owned ranches and one ejido in the northern part of Chihuahua, Mexico, using camera trapping equipment. We obtained five new records of the species as well as one account of a potential collaborative interaction between two males. These records show the use of temperate environments and higher elevations, which contrast with published literature, as this species is commonly associated with tropical and sub‐tropical environments below 1200 m. We highlight the importance of the area and the need for it to be taken into consideration when developing models and conservation strategies.

Abstract

Homo erectus remains have been found in Africa, Eurasia and Southeast Asia dating back around two million years; however, owing to their age and state of preservation, obtaining informative molecular data from them has proved challenging. Here we successfully extracted and analysed ancient enamel proteins from five male and one female Middle Pleistocene H. erectus specimens from approximately 0.4 million years ago, from the Zhoukoudian, Hexian and Sunjiadong sites. All specimens from all three sites share two amino acid variants. Of these, A253G in AMBN is previously unknown and has not been identified in other human lineages, including H. erectus from Dmanisi (Georgia), Homo antecessor from Atapuerca (Spain), Denisovans, Neanderthals and modern humans. The other variant, AMBN(M273V), has previously been identified in Denisovans, and our evidence now indicates it may have been introduced through populations related to these Middle Pleistocene H. erectus. The regions in the Denisovan genome attributed to super-archaic introgression, some of which later passed to modern humans, are likely to have originated from H. erectus. Late Middle Pleistocene H. erectus may have coexisted with Denisovans in parts of East Asia, where these interactions are presumed to have occurred.

Abstract

In this study, we synthesize the known late Quaternary crocodylian record in Australasia through literature review and direct assessment of fossil and zooarchaeological material. The late Pleistocene record, mainly from Australia, consists of partial skeletal remains mostly referable to the extinct Mekosuchinae, with some attributable to Crocodylus. The youngest reliably dated mekosuchine fossil is ∼20 000 years old, suggesting mekosuchine decline and extinction coincided with that of other Australian megafauna. In contrast, three south-west Pacific islands—New Caledonia, Vanuatu, and Fiji—were Holocene refuges for mekosuchines, whose remains occur in archaeological contexts, indicating human interaction. Their extinction followed soon after human arrival, suggesting anthropogenic influence as a potential key factor. Crocodylus johnstoni occurs in palaeontological (potentially 28 kya) and archaeological sites in Australia. Crocodylus porosus has an ambiguous fossil record potentially going back over 40 kya, but is definitively present by the Holocene. Most Crocodylus remains come from coastal sites overlapping modern ranges. Archaeological evidence supports crocodile utilization by humans in Australia, Torres Strait, and New Guinea. The fragmentary nature of the known fossil material, as well as the current lack of reliable dates, leaves many unanswered questions about the morphology, palaeobiology, and disappearance of mekosuchines.

Abstract

Koalas are regionally extinct in Western Australia (WA), but their fossils have been known since 1910. Bones were previously reported from several cave deposits in the south-west of WA, Koala Cave in Yanchep and from Madura Cave on the Roe Plain. Due to the similarity of the dentition with the east coast koala (Phascolarctos cinereus), they were traditionally assumed to be the same species. Two complete additional adult skulls were collected in the past 25 years. These skulls, interpreted to belong to a male and female koala, are similar in body size to koalas from Victoria but differ markedly in being relatively much shorter in length and having obvious deeper concavities on the maxilla, below the zygomatic arch. Differences from the eastern species are also apparent in the postcranial skeleton, having less robust joints. Analysis of measurements on the skulls and teeth demonstrates quantitatively that the Western Australian koala is morphologically distinct from its east coast relative and warrants consideration as its own species. It probably went extinct in WA as a result of climate change during the late Pleistocene, which reduced eucalyptus forests to around 5% of their current cover, greatly limiting resources for food and shelter.