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Early Jurassic plesiosaur fossils from Scandinavia + Upper Cretaceous fossils from Western Desert, Egypt + feather color evolution



Ben Creisler
bcreisler@gmail.com

Some recent papers:


Sven Sachs, Jahn J. Hornung, Hans-Jürgen Lierl, and Benjamin P. Kear (2016)
Plesiosaurian fossils from Baltic glacial erratics: evidence of Early
Jurassic marine amniotes from the southwestern margin of Fennoscandia.
Geological Society Special Publication SP 434:  Mesozoic Biotas of
Scandinavia and its Arctic Territories (advance online publication)
doi:10.1144/SP434.14
http://sp.lyellcollection.org/content/early/2016/01/21/SP434.14.abstract

Early Jurassic plesiosaurian fossils are rare in the Scandinavian
region, with a few isolated bones and teeth known from Bornholm, and
anecdotal finds from East Greenland. The only other identifiable
specimens derive from Toarcian-aged (based on ammonites) erratics
deposited during Late Pleistocene glacial advances near the town of
Ahrensburg, NE of Hamburg in northern Germany. The geographical source
of these transported clasts is debated, but reconstructed ice-flow
directions and lithofacies comparisons implicate either the offshore
Baltic Sea between the Island of Bornholm and Mecklenburg–Vorpommern
(Germany) or, less probably, south of the Danish Archipelago
(Mecklenburg Bay). These regions collectively bordered the
Fennoscandian landmass and adjacent Ringkøbing-Fyn Island in the late
Early Jurassic, and were dominated by near-shore marine deltaic to
basinal settings. The Ahrensburg plesiosaurian remains include
postcranial elements reminiscent of both the microcleidid
Seeleyosaurus and the rhomaelosaurid Meyerasaurus. These occur
alongside other classic ‘Germanic province’ marine amniotes, such as
the teleosaurid crocodyliform Steneosaurus and ichthyosaurian
Stenopterygius cf. quadriscissus: thus, advocating faunal continuity
between Scandinavia and southern Germany during the Toarcian, and a
less pronounced marine reptile faunal provinciality than previously
assumed.

====

Hesham M. Sallam, Patrick M. O'Connor, Mahmoud Kora, Joseph J.W.
Sertich, Erik R. Seiffert, Mahmoud Faris, Khaled Ouda, Iman
El-Dawoudi, Sara Saber & Sanaa El-Sayed (2016)
Vertebrate paleontological exploration of the Upper Cretaceous
succession in the Dakhla and Kharga Oases, Western Desert, Egypt.
Journal of African Earth Sciences (advance online publication)
doi:10.1016/j.jafrearsci.2016.01.022
http://www.sciencedirect.com/science/article/pii/S1464343X16300334

Highlights

Vertebrate paleontological work on Qusier and Duwi formations from the
Late Cretaceous of Egypt.
The fossil bearing localities occur within the middle Campanian-early
Maastrichtian.
New age constraints on the examined rock units based on nannofossil taxa.
Fossil remains include sharks, rays, actinopterygian and
sarcopterygian fishes, turtles, and rare terrestrial archosaurians,
including dinosaurs and crocodiles.

Abstract

The Campanian and Maastrichtian stages are very poorly documented time
intervals in Africa’s record of terrestrial vertebrate evolution.
Upper Cretaceous deposits exposed in southern Egypt, near the Dakhla
and Kharga Oases in the Western Desert, preserve abundant vertebrate
fossils in nearshore marine environments, but have not yet been the
focus of intensive collection and description. Our recent
paleontological work in these areas has resulted in the discovery of
numerous new vertebrate fossil-bearing localities within the middle
Campanian Qusier Formation and the upper Campanian-lower Maastrichtian
Duwi Formation. Fossil remains recovered from the Campanian-aged
Quseir Formation include sharks, rays, actinopterygian and
sarcopterygian fishes, turtles, and rare terrestrial archosaurians,
including some of the only dinosaurs known from this interval on
continental Africa. The upper Campanian/lower Maastrichtian Duwi
Formation preserves sharks, sawfish, actinopterygians, and marine
reptiles (mosasaurs and plesiosaurs). Notably absent from these
collections are representatives of Mammalia and Avialae, both of which
remain effectively undocumented in the Upper Cretaceous rocks of
Africa and Arabia. New age constraints on the examined rock units is
provided by 23 nannofossil taxa, some of which are reported from the
Duwi Formation for the first time. Fossil discoveries from rock units
of this age are essential for characterizing the degree of endemism
that may have developed as the continent became increasingly
tectonically isolated from the rest of Gondwana, not to mention for
fully evaluating origin and diversification hypotheses of major modern
groups of vertebrates (e.g., crown birds, placental mammals).

===


Chad M. Eliason, Matthew D. Shawkey and Julia Clarke (2016)
Evolutionary shifts in the melanin-based color system of birds.
Evolution (advance online publication)
DOI: 10.1111/evo.12855
http://onlinelibrary.wiley.com/doi/10.1111/evo.12855/abstract

Melanin pigments contained in organelles (melanosomes) impart earthy
colors to feathers. Such melanin-based colors are distributed across
birds and thought to be the ancestral color-producing mechanism in
birds. However, we have had limited data on melanin-based color and
melanosome diversity in Palaeognathae, which includes the flighted
tinamous and large-bodied, flightless ratites and is the sister taxon
to all other extant birds. Here, we use scanning electron microscopy
and spectrophotometry to assess melanosome morphology and quantify
reflected color for 19 species within this clade. We find that brown
colors in ratites are uniquely associated with elongated melanosomes
nearly identical in shape to those associated with black colors.
Melanosome and color diversity in large-bodied ratites is limited
relative to other birds (including flightless penguins) and
smaller-bodied basal maniraptoran dinosaur outgroups of Aves, whereas
tinamous show a wider range of melanosome forms similar to neognaths.
The repeated occurrence of novel melanosome forms in the
non-monophyletic ratites suggests that melanin-based color tracks
changes in body size, physiology or other life history traits
associated with flight loss, but not feather morphology. We further
anticipate these findings will be useful for future color
reconstructions in extinct species, as variation in melanosome shape
may potentially be linked to a more nuanced palette of melanin-based
colors.