[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Cretaceous metatherians + other non-dino papers

Ben Creisler

A number of recent non-dino papers that may be of interest:

In open access:

Thomas E. Williamson, Stephen L. Brusatte & Gregory P. Wilson (2014)
The origin and early evolution of metatherian mammals: the Cretaceous record.
ZooKeys 465: 1–76
doi: 10.3897/zookeys.465.8178

Metatherians, which comprise marsupials and their closest fossil
relatives, were one of the most dominant clades of mammals during the
Cretaceous and are the most diverse clade of living mammals after
Placentalia. Our understanding of this group has increased greatly
over the past 20 years, with the discovery of new specimens and the
application of new analytical tools. Here we provide a review of the
phylogenetic relationships of metatherians with respect to other
mammals, discuss the taxonomic definition and diagnosis of Metatheria,
outline the Cretaceous history of major metatherian clades, describe
the paleobiology, biogeography, and macroevolution of Cretaceous
metatherians, and provide a physical and climatic background of
Cretaceous metatherian faunas. Metatherians are a clade of
boreosphendian mammals that must have originated by the Late Jurassic,
but the first unequivocal metatherian fossil is from the Early
Cretaceous of Asia. Metatherians have the distinctive tightly
interlocking occlusal molar pattern of tribosphenic mammals, but
differ from Eutheria in their dental formula and tooth replacement
pattern, which may be related to the metatherian reproductive process
which includes an extended period of lactation followed by birth of
extremely altricial young. Metatherians were widespread over Laurasia
during the Cretaceous, with members present in Asia, Europe, and North
America by the early Late Cretaceous. In particular, they were
taxonomically and morphologically diverse and relatively abundant in
the Late Cretaceous of western North America, where they have been
used to examine patterns of biogeography, macroevolution,
diversification, and extinction through the Late Cretaceous and across
the Cretaceous-Paleogene (K-Pg) boundary. Metatherian diversification
patterns suggest that they were not strongly affected by a Cretaceous
Terrestrial Revolution, but they clearly underwent a severe extinction
across the K-Pg boundary.


C. Strganac, L.L. Jacobs, M.J. Polcyn, O. Mateus, T.S. Myers, J.
Salminen, S.R. May, R. Araújo, K.M. Ferguson, A. Olímpio Gonçalves,
M.L. Morais, A.S. Schulp and T. da Silva Tavares (2014)
Geological setting and paleoecology of the Upper Cretaceous Bench 19
Marine Vertebrate Bonebed at Bentiaba, Angola.
Netherlands Journal of Geosciences  (advance online publication)
DOI: http://dx.doi.org/10.1017/njg.2014.32

The Bench 19 Bonebed at Bentiaba, Angola, is a unique concentration of
marine vertebrates preserving six species of mosasaurs in sediments
best correlated by magnetostratigraphy to chron C32n.1n between 71.4
and 71.64 Ma. The bonebed formed at a paleolatitude near 24°S, with an
Atlantic width at that latitude approximating 2700 km, roughly half
that of the current width. The locality lies on an
uncharacteristically narrow continental shelf near transform faults
that controlled the coastal outline of Africa in the formation of the
South Atlantic Ocean. Biostratigraphic change through the Bentiaba
section indicates that the accumulation occurred in an ecological time
dimension within the 240 ky bin delimited by chron 32n.1n. The fauna
occurs in a 10 m sand unit in the Mocuio Formation with bones and
partial skeletons concentrated in, but not limited to, the basal 1–2
m. The sediment entombing the fossils is an immature feldspathic sand
shown by detrital zircon ages to be derived from nearby granitic
shield rocks. Specimens do not appear to have a strong preferred
orientation and they are not concentrated in a strand line. Stable
oxygen isotope analysis of associated bivalve shells indicates a water
temperature of 18.5°C. The bonebed is clearly mixed with scattered
dinosaur and pterosaur elements in a marine assemblage. Gut contents,
scavenging marks and associated shed shark teeth in the Bench 19 Fauna
indicate biological association and attrition due to feeding
activities. The ecological diversity of mosasaur species is shown by
tooth and body-size disparity and by δ13C analysis of tooth enamel,
which indicate a variety of foraging areas and dietary niches. The
Bench 19 Fauna was formed in arid latitudes along a coastal desert
similar to that of modern Namibia on a narrow, tectonically controlled
continental shelf, in shallow waters below wave base. The area was
used as a foraging ground for diverse species, including molluscivorus
Globidens phosphaticus, small species expected near the coast,
abundant Prognathodon kianda, which fed on other mosasaurs at Bench
19, and species that may have been transient and opportunistic feeders
in the area.


Marek Narkiewicz, Jacek Grabowski, Katarzyna Narkiewicz, Grzegorz
Niedźwiedzki, Gregory J. Retallack, Piotr Szrek & David De
Vleeschouwer (2014)
Palaeonvironments of the Eifelian dolomites with earliest tetrapod
trackways (Holy Cross Mountains, Poland).
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)


The earliest tetrapod trackways were formed in shallow-water lagoonal
dolomite muds
The tideless Zachełmie lagoons were surrounded by sparsely vegetated
islands or spits
In most cases the animals were at least partly submerged while wading
or swimming
Limbs developed probably among aquaeous animals, predating their


The Eifelian dolomites in the Zachełmie Quarry (Holy Cross Mountains,
Poland) contain trackways and tracks of tetrapods 390-391 Ma old, and
thus the oldest known so far. The environments of the trackway-bearing
beds have been investigated using sedimentological, palaeontological,
geochemical and palaeomagnetic methods. The reconstructed tetrapod
habitats comprised shallow-water lagoons separated from an open marine
basin by sparsely vegetated islands and spits. The lagoonal waters
were well-aerated and a few-meters deep at most, undergoing periodic
desiccation. The dolomitic sediments, primarily of microbial origin,
formed in tropical waters of slightly modified marine composition.
Oxygen isotope data obtained from the dolomicrites suggest water
temperatures around 30 °C. The seasonal semi-arid to subhumid climate,
deduced from paleosol characteristics, was probably of a tropical
monsoonal type. The degree of restriction of the lagoonal system
evolved from relatively open, evaporation-dominated towards
increasingly closed, fresh-water influenced.


James A. Doyle (2014)
Historical Biology (advance online publication)
Recognising angiosperm clades in the Early Cretaceous fossil record.

Studies of the earliest Cretaceous angiosperms in the 1970s made only
broad comparisons with living taxa, but discoveries of fossil flowers
and increasingly robust molecular phylogenies of living angiosperms
allow more secure recognition of extant clades. The middle to late
Albian rise of tricolpate pollen and the first local dominance of
angiosperm leaves mark the influx of near-basal lines of eudicots.
Associated flowers indicate that palmately lobed ‘platanoids’ and
Sapindopsis are both stem relatives of Platanus, while Nelumbites was
related to Nelumbo (also Proteales) and Spanomera to Buxaceae.
Monocots are attested by Aptian Liliacidites pollen and Acaciaephyllum
leaves and Albian araceous inflorescences. Several Albian–Cenomanian
fossils belong to Magnoliidae in the revised monophyletic sense,
including Archaeanthus in Magnoliales and Virginianthus and Mauldinia
in Laurales, while late Barremian pollen tetrads (Walkeripollis) are
related to Winteraceae. In the basal ANITA grade, Nymphaeales are
represented by Aptian and Albian flowers and whole plants
(Monetianthus, Carpestella and Pluricarpellatia). Epidermal
similarities of lower Potomac leaves to woody members of the ANITA
grade are consistent with Albian flowers assignable to
Austrobaileyales (Anacostia). Aptian to Cenomanian mesofossils
represent both crown group Chloranthaceae (Asteropollis plant) and
stem relatives of Chloranthaceae and/or Ceratophyllum (Canrightia,
Zlatkocarpus, Pennipollis plant and possibly Appomattoxia).


Ove Eriksson (2014)
Evolution of angiosperm seed disperser mutualisms: the timing of
origins and their consequences for coevolutionary interactions between
angiosperms and frugivores
Biological Reviews (advance online publication)
DOI: 10.1111/brv.12164

The origins of interactions between angiosperms and fruit-eating seed
dispersers have attracted much attention following a seminal paper on
this topic by Tiffney (1984). This review synthesizes evidence
pertaining to key events during the evolution of angiosperm–frugivore
interactions and suggests some implications of this evidence for
interpretations of angiosperm–frugivore coevolution. The most
important conclusions are: (i) the diversification of angiosperm seed
size and fleshy fruits commenced around 80 million years ago (Mya).
The diversity of seed sizes, fruit sizes and fruit types peaked in the
Eocene around 55 to 50 Mya. During this first phase of the
interaction, angiosperms and animals evolving frugivory expanded into
niche space not previously utilized by these groups, as frugivores and
previously not existing fruit traits appeared. From the Eocene until
the present, angiosperm–frugivore interactions have occurred within a
broad frame of existing niche space, as defined by fruit traits and
frugivory, motivating a separation of the angiosperm–frugivore
interactions into two phases, before and after the peak in the early
Eocene. (ii) The extinct multituberculates were probably the most
important frugivores during the early radiation phase of angiosperm
seeds and fleshy fruits. Primates and rodents are likely to have been
important in the latter part of this first phase. (iii) Flying
frugivores, birds and bats, evolved during the second phase, mainly
during the Oligocene and Miocene, thus exploiting an existing
diversity of fleshy fruits. (iv) A drastic climate shift around the
Eocene–Oligocene boundary (around 34 Mya) resulted in more semi-open
woodland vegetation, creating patchily occurring food resources for
frugivores. This promoted evolution of a ‘flying frugivore niche’
exploited by birds and bats. In particular, passerines became a
dominant frugivore group worldwide. (v) Fleshy fruits evolved at
numerous occasions in many angiosperm families, and many of the
originations of fleshy fruits occurred well after the peak in the
early Eocene. (vi) During periods associated with environmental change
altering coevolutionary networks and opening of niche space,
reciprocal coevolution may result in strong directional selection
formative for both fruit and frugivore evolution. Further evidence is
needed to test this hypothesis. Based on the abundance of plant
lineages with various forms of fleshy fruits, and the diversity of
frugivores, it is suggested that periods of rapid coevolution in
angiosperms and frugivores occurred numerous times during the 80
million years of angiosperm–frugivore evolution.