The osteology of ‘Periptychus carinidens’: a robust, ungulate-like placental mammal (Mammalia: Periptychidae) from the Paleocene of North America

Periptychus is the archetypal genus of Periptychidae, a clade of prolific Paleocene 'condylarth' mammals from North America that were among the first placental mammals to radiate after the end-Cretaceous extinction, remarkable for their distinctive dental anatomy. A comprehensive understanding of the anatomy of Periptychus has been hindered by a lack of cranial and postcranial material and only cursory description of existing material. We comprehensively describe the cranial, dental and postcranial anatomy of Periptychus carinidens based on new fossil material from the early Paleocene (Torrejonian) of New Mexico, USA. The cranial anatomy of Periptychus is broadly concurrent with the inferred plesiomorphic eutherian condition, albeit more robust in overall construction. The rostrum is moderately elongate with no constriction, the facial region is broad, and the braincase is small with a well-exposed mastoid on the posterolateral corner and tall sagittal and nuchal crests. The dentition of Periptychus is characterized by strongly crenulated enamel, enlarged upper and lower premolars with a tall centralised paracone/protoconid. The postcranial skeleton of Periptychus is that of a robust, medium-sized (~20 Kg) stout-limbed animal that was incipiently mediportal and adopted a plantigrade stance. The structure of the fore- and hindlimb of Periptychus corresponds to that of a typically terrestrial mammal, while morphological features of the forelimb such as the low tubercles of the humerus, long and prominent deltopectoral crest, pronounced medial epicondyle, and hemispherical capitulum indicate some scansorial and/or fossorial ability. Most striking is the strongly dorsoplantarly compressed astragalus of Periptychus, which in combination with the distal crus and calcaneal morphology indicates a moderately mobile cruropedal joint. The anatomy of Periptychus is unique and lacks any extant analogue; it combines a basic early placental body plan with numerous unique specializations in its dental, cranial and postcranial anatomy that exemplify the ability of mammals to adapt and evolve following catastrophic environmental upheaval

Durham University and its role in Malta's development planning during the 1950s through applied research

In the 1950s the University of Durham was involved in a number of separate externally-funded projects that were aimed at assessing Malta's potential for development after it became independent from the United Kingdom. Following a pilot study, a group led by W.B. Fisher of the Department of Geography together with a team from the University of Malta, obtained what at the time were substantial funds from the Colonial Office's Colonial Economic Research Committee (CERC). Concurrently K.C. Dunham, Head of the Department of Geology, successfully obtained support from British Petroleum to carry out a geological survey, while a soil survey was separately commissioned. As well as marking the first of what was to become an established tradition of applied development projects in the eastern Mediterranean and Middle East, the Durham Geography Department also used its growing profile of external funding to stimulate an expansion of both its teaching and its research, so as to become one of the largest departments in the United Kingdom. Reflecting the zeitgeist of the time, Fisher and his colleagues viewed applied research, not only as an academic exercise but also as a route to human betterment, and perceived the researchers' task as providing information and policy options upon which decisions makers may formulate policy. They eschewed any attempt to fully consider different development strategies. However, some younger researchers in their later outputs and doctoral theses adopted a more critical approach about the options for Malta's future. The principal issue raised by Durham team was a concern that post-independence Malta was facing a Malthusian trap in which the islands would not have a sufficiently productive resource base to support its growing population. Over the past six decades the trap has been avoided because of a growing economy, but today pressures of people on resources are once more acute and a case is made for a second land-use survey

Letter. Episodic fresh surface waters in the Eocene Arctic Ocean

It has been suggested, on the basis of modern hydrology and fully coupled palaeoclimate simulations, that the warm greenhouse conditions that characterized the early Palaeogene period (55–45 Myr ago) probably induced an intensified hydrological cycle with precipitation exceeding evaporation at high latitudes. Little field evidence, however, has been available to constrain oceanic conditions in the Arctic during this period. Here we analyse Palaeogene sediments obtained during the Arctic Coring Expedition, showing that large quantities of the free-floating fern Azolla grew and reproduced in the Arctic Ocean by the onset of the middle Eocene epoch (50 Myr ago). The Azolla and accompanying abundant freshwater organic and siliceous microfossils indicate an episodic freshening of Arctic surface waters during an 800,000-year interval. The abundant remains of Azolla that characterize basal middle Eocene marine deposits of all Nordic seas probably represent transported assemblages resulting from freshwater spills from the Arctic Ocean that reached as far south as the North Sea. The termination of the Azolla phase in the Arctic coincides with a local sea surface temperature rise from 10°C to 13°C, pointing to simultaneous increases in salt and heat supply owing to the influx of waters from adjacent oceans. We suggest that onset and termination of the Azolla phase depended on the degree of oceanic exchange between Arctic Ocean and adjacent seas