THE CRETACEOUS SKELETON COAST OF ANGOLA JACOBS, Louis, SMU, Dallas, TX, USA; POLCYN, Michael, SMU, Dallas, TX, USA; MATEUS, Octávio, Museu da Lourinhã, Lourinhã, Portugal; SCHULP, Anne, Natuurhistorisch Museum Maastricht, Maastricht, Netherlands; NETO, André , Universidade Agostinho Neto, Luanda, Angola Cretaceous coastal sediments of Angola present a rich and diverse fauna of marine amniotes, including turtles, mosasaurs, and plesiosaurs. The abundance of mosasaurs in particular suggests a highly productive coastal area. Angola today lies at the northern limit of the Namibian Desert, the so-called Skeleton Coast, which results from prevailing southeasterly winds of the descending limb of the southern Hadley Cell sweeping across the African coast. The Benguela upwelling and a highly productive sea are found today off the Namibian Desert coast. However, the Benguela upwelling system, based on results of DSDP studies, is said to have originated in the late Neogene and therefore cannot explain the productivity found along the length of the West African coast. The explanation is found in the northward drift of Africa through the arid climate zone, and is demonstrated by the tracing of the paleogeographic position of fossil localities through time.

A new Late Cretaceous turtle, Angolachelys mbaxi gen. et sp. nov., from the Turonian (90 Mya) of Angola, represents the oldest eucryptodire from Africa. Phylogenetic analysis recovers Angolachelys mbaxi as the sister taxon of Sandownia harrisi from the Aptian of Isle of Wight, England. An unnamed turtle from the Albian Glen Rose Formation of Texas (USA) and the Kimmeridgian turtle Solnhofia parsonsi (Germany), are successively more distant sister taxa. Bootstrap analysis suggests those four taxa together form a previously unrecognized monophyletic clade of marine turtles, herein named Angolachelonia clade nov., supported by the following synapomorphies: mandibular articulation of quadrate aligned with or posterior to the occiput, and basisphenoid not visible or visibility greatly reduced in ventral view. Basal eucryptodires and angolachelonians originated in the northern hemisphere, thus Angolachelys represents one of the first marine amniote lineages to have invaded the South Atlantic after separation of Africa and South America.

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