New data on the microvertebrate fauna from the Upper Jurassic or lowest Cretaceous of Ksar Metlili (Anoual Syncline, eastern Morocco)

The Middle Jurassic – Early Cretaceous period witnessed the emergence of some major representatives of modern continental vertebrate groups (stem lissamphibians, squamates, therian mammals and birds) and angiosperms, at a time when fragmentation of Pangaea was underway. The successive Moroccan microvertebrate faunas of Ksar Metlili (?Berriasian) and Guelb el Ahmar (Bathonian) from the Anoual Syncline significantly improve our poor knowledge of Gondwanan and especially African palaeobiodiversity at this time. They are among the richest known from the Mesozoic of Gondwana, and are well placed in northwestern Africa to record faunal interchanges with Laurasia. Here we focus on the Ksar Metlili fauna, first documented in the 1980s and most recently resampled in 2010, which produced 24 541 microremains representing 47 species of 8 main groups (Chondrichthyes, Actinopterygii, Sarcopterygii, Lissamphibia, Lepidosauromorpha, Testudinata, Archosauromorpha and Synapsida). It includes remarkable taxa: the oldest stem boreosphenidan mammals from Gondwana, probably some of the last non-mammaliaform cynodonts, a basal ornithischian, possibly freshwater teleosaurid crocodylomorphs, and some of the rare occurrences of choristoderes and albanerpetontids in Gondwana. Comparison of the Ksar Metlili fauna with that of Guimarota (Kimmeridgian, Portugal) further provides evidence of numerous shared taxa of Laurasian affinities, in contrast to the occurrence of few taxa with Gondwanan affinities. This suggests complex palaeobiogeographical relationships – implying both vicariance and dispersal events – of North Africa within Gondwana at the Jurassic–Cretaceous transition. Finally, the faunal similarities with the Guelb el Ahmar fauna question the Cretaceous age of the Ksar Metlili fauna, suggesting an alternative possible Late Jurassic age.

Araceae, a Family with Great Potential

This paper highlights the most unique characteristics of Araceae: their high species diversity, high habit diversity, high rates of endemism, and high rates of new species discovery. Also discussed is the origin of the family in the Early Cretaceous period and its modern-day worldwide distribution, which shows high generic diversity in Asia and high species diversity in South America. The last 40 years have shown dramatic increases in the number of species known for most of the Neotropical genera but with most of the growth coming from Central America. The development of computerized determination keys has led to the realization that many more species are likely to be new to science. This study also recommends future directions and localities or regions where most aroid research should be concentrated.

Flood analysis of the Limpopo River basin through past evolution reconstruction and a geomorphological approach

This research reconstructs the past evolution of the Limpopo River, a transboundary system located in south-eastern Africa, and describes its geomorphological settings through a literature review and field work activities, with the aim of analysing flood hazard in the basin. Major changes have occurred since the late Jurassic–early Cretaceous period due to successive tectonic events. The paper demonstrates that the apparently abandoned drainage conformation of the palaeo-Limpopo in the upper and middle stretches of the river today constitutes preferential flood-prone areas in the case of major rainfall events. An important palaeo-delta is identified in the lower Limpopo, which imposes a particular drainage pattern onto the floodplain in Mozambique and influences the flood dynamics at present. The adopted method is helpful in determining flood hazard in a data-scarce area showing complex fluvial dynamics, and allows for the identification of unsuitable locations for human settlements.

Flood risk analysis of the Limpopo River basin through past evolution reconstruction and geomorphological approach

This research reconstructs the past evolution of the Limpopo River, a transboundary system located in south-eastern Africa, and describes its geomorphological settings through literature review and field work activities, with aim to analyse the risk of floods in the basin. Major changes have occurred since the late Jurassic – early Cretaceous period due to successive tectonic events. The paper demonstrates that the apparently abandoned drainage conformation of the palaeo-Limpopo in the upper and middle stretches of the river constitutes today preferential flood-prone areas in case of major rainfall events. An important palaeo-delta is identified in the lower Limpopo, which imposes a particular drainage pattern to the floodplain in Mozambique and influences the floods dynamics at present. The adopted method is helpful in determining flood risk in a data-scarce area showing complex fluvial dynamics, and allows identifying unsuitable locations for human settlements.

Late Jurassic-Early Cretaceous faulting in the Southeastern French basin: does it reflect a tectonic reorganization?

We present new data constraining the Late Jurassic to Early Cretaceous evolution of the Southeastern French basin (SFB). Meso-scale faults with displacement of several decimeters to 1–2 meters were sampled for geometric and kinematic data analysis and the faulted and un-faulted sedimentary units were examined for sedimentologic and bio-stratigraphic purposes. Small-scale faults were also extensively collected to determine the local stress states during this period. Meso-scale normal faults formed during sediment deposition or before its complete lithification attest of a recurrent activity in the Late Jurassic to Early Cretaceous period in an overall extensional context. The fault network cutting the Oxfordian to Aptian sequences included normal faults of various trends, ranging between WSW-ENE and NNW-SSE. We show that the deformation mechanism in the SFB drastically changed in the Jurassic-Cretaceous transition (latermost Tithonian?), with the direction of extension rotating from a WNW-ESE to a NNE-SSW direction. Lateral thickness variation of the sequences, redistribution of sediments, faulting at various scales concur that the Early Cretaceous period marks a tectono-stratigraphic reorganization of the basin. We suggest that it traduces the rifting and later opening of the North Atlantic (main branch and bay of Biscay branch).

Late Cretaceous and Danian limestone

At the termination of the Early Cretaceous period, the sea transgressed large earlier land areas. The transgression, the reduced relief of the continents, the generally diminished tectonic activity, the climatic change, and the enormous production of calcareous nannoplankton in the oceans profoundly changed the gross facies pattern in the North Sea region. The elastic sedimentation was replaced during Late Cretaceous time by offshore relatively deep water carbonate sedimentation. This resulted in the deposition of a chalk sequence reaching a thickness of 1-2 km in the Danish Subbasin and the North Sea area.