M.-L. Morais

Agostinho Neto University

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Octávio Mateus

Universidade Nova de Lisboa

Michael J. Polcyn

Southern Methodist University

Louis L. Jacobs

Southern Methodist University

António Olímpio Gonçalves

Agostinho Neto University

C. Strganac

Perot Museum of Nature and Science

Anne S. Schulp

Naturalis Biodiversity Center

Ricardo Araújo

University of Lisbon

Ao. Gonçalves

Tatiana da Silva Tavares

Université de Bourgogne

L. Jacobs

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Southern Methodist University

Museu da Lourinhã

Departamento de Ciência e Tecnologia

Universidade Nova de Lisboa

Terra

Agostinho Neto University

Utrecht University

University of Lisbon

University of Coimbra

Stress Environnementaux et Biosurveillance des Milieux Aquatiques

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New aristonectine elasmosaurid plesiosaur specimens from the Early Maastrichtian of Angola and comments on paedomorphism in plesiosaurs

Netherlands Journal of Geosciences – Geologie en Mijnbouw (2015)

Ricardo Araújo Michael J. Polcyn Johan Lindgren Louis L. Jacobs Anne S. Schulp

Abstract New elasmosaurid plesiosaur specimens are described from the Early Maastrichtian of Angola. Phylogenetic analyses reconstruct the Angolan taxon as an aristonectine elasmosaurid and the sister taxon of an unnamed form of similar age from New Zealand. Comparisons also indicate a close relationship with an unnamed form previously described from Patagonia. All of these specimens exhibit an ostensibly osteologically immature external morphology, but histological analysis of the Angolan material suggests an adult with paedomorphic traits. By extension, the similarity of the Angolan, New Zealand and Patagonian material indicates that these specimens represent a widespread paedomorphic yet unnamed taxon.

Neoteny

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10.1017/njg.2014.43

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Carbon isotope stratigraphy and 40Ar/39Ar age of the Cretaceous South Atlantic coast, Namibe Basin, Angola

Journal of African Earth Sciences (2014)

C. Strganac Johanna Salminen L. Jacobs K. Ferguson Michael J. Polcyn

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A new elasmosaurid from the early Maastrichtian of Angola and the implications of girdle morphology on swimming style in plesiosaurs

Netherlands Journal of Geosciences – Geologie en Mijnbouw (2015)

Ricardo Araújo Michael J. Polcyn Anne S. Schulp Octávio Mateus Louis L. Jacobs

Abstract We report here a new elasmosaurid from the early Maastrichtian at Bentiaba, southern Angola. Phylogenetic analysis places the new taxon as the sister taxon to Styxosaurus snowii , and that clade as the sister of a clade composed of ( Hydrotherosaurus alexandrae ( Libonectes morgani + Elasmosaurus platyurus )). The new taxon has a reduced dorsal blade of the scapula, a feature unique amongst elasmosaurids, but convergent with cryptoclidid plesiosaurs, and indicates a longitudinal protraction-retraction limb cycle rowing style with simple pitch rotation at the glenohumeral articulation. Morphometric phylogenetic analysis of the coracoids of 40 eosauropterygian taxa suggests that there was a broad range of swimming styles within the clade.

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10.1017/njg.2014.44

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Stable oxygen isotope chemostratigraphy and paleotemperature regime of mosasaurs at Bentiaba, Angola

Netherlands Journal of Geosciences – Geologie en Mijnbouw (2015)

C. Strganac Louis L. Jacobs Michael J. Polcyn Kurt M. Ferguson Octávio Mateus

Abstract Stable oxygen isotope values of inoceramid marine bivalve shells recovered from Bentiaba, Angola, are utilised as a proxy for paleotemperatures during the Late Cretaceous development of the African margin of the South Atlantic Ocean. The δ 18 O values derived from inoceramids show a long-term increase from –3.2‰ in the Late Turonian to values between –0.8 and –1.8‰ in the Late Campanian. Assuming a constant oceanic δ 18 O value, an ∼2‰ increase may reflect cooling of the shallow marine environment at Bentiaba by approximately 10°. Bentiaba values are offset by about +1‰ from published records for bathyal Inoceramus at Walvis Ridge. This offset in δ 18 O values suggests a temperature difference of ∼5° between coastal and deeper water offshore Angola. Cooler temperatures implied by the δ 18 O curve at Bentiaba coincide with the stratigraphic distribution of diverse marine amniotes, including mosasaurs, at Bentiaba.

10.1017/njg.2015.1

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Citations (13)