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Daptocephalus Assemblage Zone revised + bird body mass + Depéret’s Rule + more

Ben Creisler

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

Pia A. Viglietti, Roger M.H. Smith, Kenneth D. Angielczyk, Christian
F. Kammerer, Jörg Fröbisch & Bruce S. Rubidge (2015)
The Daptocephalus Assemblage Zone (Lopingian), South Africa: A
proposed biostratigraphy based on a new compilation of stratigraphic
Journal of African Earth Sciences (advance online publication)


First detailed stratigraphic ranges of Late Permian tetrapods from the
Karoo Basin.

Reinstatement of the Daptocephalus Assemblage Zone required based on

New stratigraphic ranges call for subdivision of the Daptocephalus
Assemblage Zone.

Refined biostratigraphy will assist in global Late Permian correlation.


The Dicynodon Assemblage Zone (DiAZ) of South Africa’s Karoo Basin is
one of the eight biostratigraphic zones of the Beaufort Group. It
spans the uppermost Permian strata (Balfour, Teekloof, and Normandien
formations) and traditionally has been considered to terminate with
the disappearance of Dicynodon lacerticeps at the Permo-Triassic
Boundary. We demonstrate that the three index fossils currently used
to define the Dicynodon Assemblage Zone (Dicynodon lacerticeps,
Theriognathus microps, and Procynosuchus delaharpeae) have first
appearance datums (FADs) below its traditionally recognized lower
boundary and have ranges mostly restricted to the lower portion of the
biozone, well below the Permo-Triassic Boundary. We propose
re-establishing Daptocephalus leoniceps as an index fossil for this
stratigraphic interval, and reinstating the name Daptocephalus
Assemblage Zone (DaAZ) for this unit. Furthermore, the FAD of
Lystrosaurus maccaigi in the uppermost reaches of the biozone calls
for the establishment of a two-fold subdivision of the current
Dicynodon Assemblage Zone. The biostratigraphic utility of
Daptocephalus leoniceps and other South African dicynodontoids outside
of the Karoo Basin is limited due to basinal endemism at the species
level, and varying temporal ranges of dicynodontoids globally.
Therefore we recommend their use only for correlation within the Karoo
Basin at this time. Revision of the stratigraphic ranges of all late
Permian tetrapods does not reveal a significant change in faunal
diversity between the lower and upper DaAZ. However, the last
appearance datums of the abundant taxa Dicynodon lacerticeps,
Theriognathus microps, Procynosuchus delaharpeae, and Diictodon
feliceps occur below the three extinction phases associated with the
end-Permian mass extinction event. Due to northward attenuation of the
strata, the stratigraphic position of the extinction phases may need
to be reconsidered in these areas where late Permian lithostratigraphy
has not been affected by attenuation and frequent hiatuses.


Ricardo N. Melchor (2015)
Application of vertebrate trace fossils to palaeoenvironmental analysis.
Palaeogeography, Palaeoclimatology, Palaeoecology 439: 79–96


Palaeoenvironmental analysis can benefit from the use of vertebrate
trace fossils.

More experimentation and observations are needed to understand
footprint formation.

Some vertebrate trace fossils are linked to specific environments.

Vertebrate ichnofabrics can add significant information to
environmental analysis.

As currently defined, most vertebrate ichnofacies add little data on
the environment.


This is a review of the main uses of vertebrate trace fossils,
ichnofabrics and ichnofacies in the palaeoenvironmental analysis of
sedimentary sequences. The article accounts for the significant
developments produced in the last three decades, including the
application of the ichnofacies concept to vertebrate trace fossils.
Recognition of footprints in cross-sectional view and their
distinction from inorganic structures and burrow fills, is first
discussed. The response of different substrates, showing contrasting
water content and imprinted by different animals or devices, is
compared in terms of the morphology of the resultant footprint.
Trackways with sand crescents are typical of aeolian cross-strata and
are absent in associated flat-lying to low-angle deposits. Thick
packages of highly bioturbated sandy dune and interdune sediments have
been interpreted as reflecting periods of increased rainfall.
Neoichnological observations in modern lake basins suggest that
distinct zones can be recognized in the margins of fossil ponds and
lakes, including onshore, shoreline and shallow subaqueous zones.
Abundant flamingo-like footprints and flamingo nest mounds are good
indicators of alkaline and/or saline lake waters. Hippopotamus trails
are found closely associated with modern and fossil freshwater
wetlands. Dinosaur and pterosaur swim traces from lacustrine and
fluvial deposits can be used to estimate water depth. Turtle,
crocodile, amphibian, hippopotamus and fish swim traces allow one to
infer a subaqueous substrate. Certain modern intertidal fish feeding
traces are oriented with the predominant tidal current and can be used
as palaeocurrent indicators. The preferential orientation of tetrapod
trackways in lacustrine and fluvial deposits is analyzed. Vertebrate
trace fossils can help to infer discharge variability in fluvial
channels. The descriptions of vertebrate ichnofabrics are commonly
limited to heavily bioturbated beds due to trampling by vertebrates,
and to a few examples of ichnofabrics with discrete trace fossils. The
nature and implications of the recognized vertebrate ichnofacies are
still being debated and have a limited utility in palaeoenvironmental
analysis. The distinction of a potential vertebrate burrow ichnofacies
in carbonate-bearing palaeosols is proposed to represent well-drained
soils, developed under arid or semiarid climate.


Elizabeth Martin-Silverstone, Orsolya Vincze, Ria McCann, Carl H. W.
Jonsson, Colin Palmer, Gary Kaiser, & Gareth Dyke (2015)
Exploring the Relationship between Skeletal Mass and Total Body Mass in Birds.
PLoS ONE 10(10): e0141794
doi: 10.1371/journal.pone.0141794

Total body mass (TBM) is known to be related to a number of different
osteological features in vertebrates, including limb element
measurements and total skeletal mass. The relationship between
skeletal mass and TBM in birds has been suggested as a way of
estimating the latter in cases where only the skeleton is known (e.g.,
fossils). This relationship has thus also been applied to other
extinct vertebrates, including the non-avian pterosaurs, while other
studies have used additional skeletal correlates found in modern birds
to estimate TBM. However, most previous studies have used TBM compiled
from the literature rather than from direct measurements, producing
values from population averages rather than from individuals. Here, we
report a new dataset of 487 extant birds encompassing 79 species that
have skeletal mass and TBM recorded at the time of collection or
preparation. We combine both historical and new data for analyses with
phylogenetic control and find a similar and well-correlated
relationship between skeletal mass and TBM. Thus, we confirm that TBM
and skeletal mass are accurate proxies for estimating one another. We
also look at other factors that may have an effect on avian body mass,
including sex, ontogenetic stage, and flight mode. While data are
well-correlated in all cases, phylogeny is a major control on TBM in
birds strongly suggesting that this relationship is not appropriate
for estimating the total mass of taxa outside of crown birds,
Neornithes (e.g., non-avian dinosaurs, pterosaurs). Data also reveal
large variability in both bird skeletal and TBM within single species;
caution should thus be applied when using published mass to test
direct correlations with skeletal mass and bone lengths.


Dinosaur body mass



Folmer Bokma, Marc Godinot, Olivier Maridet, Sandrine Ladevèze, Loïc
Costeur, Floréal Solé, Emmanuel Gheerbrant, Stéphane Peigné, Florian
Jacques, and Michel Laurin (2015)
Testing for Depéret’s Rule (body size increase) in Mammals using
Combined Extinct and Extant Data.
Systematic Biology (advance online publication)


Whether or not evolutionary lineages in general show a tendency to
increase in body size has often been discussed. This tendency has been
dubbed “Cope’s rule” but because Cope never hypothesized it, we
suggest renaming it after Depéret, who formulated it clearly in 1907.
Depéret’s rule has traditionally been studied using fossil data, but
more recently a number of studies have used present-day species. While
several paleontological studies of Cenozoic placental mammals have
found support for increasing body size, most studies of extant
placentals have failed to detect such a trend. Here we present a
method to combine information from present-day species with fossil
data in a Bayesian phylogenetic framework. We apply the method to body
mass estimates of a large number of extant and extinct mammal species,
and find strong support for Depéret’s rule. The tendency for size
increase appears to be driven not by evolution towards larger size in
established species, but by processes related to the emergence of new
species. Our analysis shows that complementary data from extant and
extinct species can greatly improve inference of macroevolutionary


Pavel P. Skutschas (2015)
A new crown-group salamander from the Middle Jurassic of Western
Siberia, Russia.
Palaeobiodiversity and Palaeoenvironments (advance online publication)
DOI: 10.1007/s12549-015-0216-x

A new crown-group salamander, Kiyatriton krasnolutskii sp. nov., from
the Middle Jurassic (Bathonian) Itat Formation of the Berezovsk Quarry
locality in Western Siberia, Russia, is described on the basis of new
material and a dentary fragment previously referred to the undescribed
salamander taxon “Berezovsk salamander B” (sensu Skutschas 2013).
Kiyatriton krasnolutskii sp. nov. differs from K. leshchinskiyi (type
species of the genus Kiyatriton) in that the ventrolateral ridges on
the atlas are sharper anteriorly, more ventrally oriented and reach
the anterior cotylar rims and that the dentary has a relatively taller
dental parapet. Kiyatriton krasnolutskii sp. nov. is one of the oldest
salamanders in the fossil record. The finding of Kiyatriton
krasnolutskii sp. nov. in Berezovsk Quarry is significant for: (1)
clarifying that the previously reported “Berezovsk salamander B” is a
crown-group salamander of the genus Kiyatriton; (2) extending the
stratigraphic range of the genus Kiyatriton backward some 40 million
years into the Bathonian, from the previously youngest record in the
Aptian–Albian; (3) indicating that K. leshchinskiyi from the
Aptian–Albian Shestakovo locality in Western Siberia, Russia, survived
as a relic into the Early Cretaceous of present-day Western Siberia;
(4) supporting the hypothesis that Bathonian vertebrate faunas of
Europe and Western Siberia were homogeneous; and (5) suggesting that
all Bathonian crown-group salamanders in Asia could be members of one
cryptobranchoid clade and could represent the first radiation of