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Ichthyopterygia limb centralia + Gastornis diet evidence from egg shells + more
A number of recent non-dino papers that may be of interest:
Ryosuke Motani, Da-Yong Jiang, Andrea Tintori, Olivier Rieppel,
Guan-Bao Chen & Hailu You (2015)
First evidence of centralia in Ichthyopterygia reiterating bias from
paedomorphic characters on marine reptile phylogenetic reconstruction.
Journal of Vertebrate Paleontology (advance online publication)
>From the text:
The present report adds another example of centralia being lost within
a clade of marine reptiles after marine invasion. This leaves
Sauropterygia as the only clade for which a basal member with manual
centralia is unknown, although such may not be the case if
saurosphargids are basal to Sauropterygia as proposed by Li et al.
(2014). The inferred presence of centralia in the hind limb of
Chaohusaurus suggests that pedal centralia loss occurred independently
at least in Ichthyopterygia and thalattosaurs (Muller et al., 2005).
Fossils Cretaceous turtles from Belgium
A. Pérez-García (2015)
Dos ejemplares inéditos de tortugas hallados en el siglo XIX en el
Cretácico Inferior de Bernissart (Bélgica). [Two undescribed
specimens of turtles found in the nineteenth century in the Early
Cretaceous levels of Bernissart (Belgium) ]
Geogaceta 57: 67-70
Unpublished turtle specimens found in the nineteenth century in the
Early Cretaceous levels of Bernissart (Belgium) are analyzed here.
They correspond to juvenile individuals. The new evidence provided by
these specimens sheds new light on the systematic position of the
juvenile individuals coming from that locality, which had recently
been assigned to Chelonii indet. These specimens are reassigned to cf.
I. G. Danilov & E. M. Obraztsova (2015)
Taxonomic position of Oxemys gutta Nessov, 1977, a problematic turtle
from the Upper Cretaceous of Uzbekistan, and basisphenoid morphology
in some groups of Late Mesozoic turtles of Asia.
Paleontological Journal 49(3): 279-292
The holotype (basisphenoid) of Oxemys gutta Nessov, 1977, a
problematic skull-based turtle taxon from the Khodzhakul Formation
(Lower Cenomanian, Upper Cretaceous, Uzbekistan) is redescribed and
its systematic position is reviewed. The literature and original
morphological data on the basisphenoid complex of some Late Mesozoic
turtles of Asia are discussed. A list of 14 characters of the
basisphenoid complex, many of which have never been used in
phylogenetic reconstructions, is provided. A comparison of O. gutta
with other Late Mesozoic turtle taxa of Asia based on these characters
shows that it is most similar to members of Macrobaenidae/Sinemydidae
and Lindholmemydidae. The analysis of possible associations of O.
gutta with shell-based turtle taxa known from the Khodzhakul Formation
suggests that it most likely belongs to Macrobaenidae/Sinemydidae.
Jennifer C. Olori (2015)
Skeletal Morphogenesis of Microbrachis and Hyloplesion (Tetrapoda:
Lepospondyli), and Implications for the Developmental Patterns of
Extinct, Early Tetrapods.
PLoS ONE 10(6): e0128333.
The ontogeny of extant amphibians often is used as a model for that of
extinct early tetrapods, despite evidence for a spectrum of
developmental modes in temnospondyls and a paucity of ontogenetic data
for lepospondyls. I describe the skeletal morphogenesis of the extinct
lepospondyls Microbrachis pelikani and Hyloplesion longicostatum using
the largest samples examined for either taxon. Nearly all known
specimens were re-examined, allowing for substantial anatomical
revisions that affect the scoring of characters commonly used in
phylogenetic analyses of early tetrapods. The palate of H.
longicostatum is re-interpreted and suggested to be more similar to
that of M. pelikani, especially in the nature of the contact between
the pterygoids. Both taxa possess lateral lines, and M. pelikani
additionally exhibits branchial plates. However, early and rapid
ossification of the postcranial skeleton, including a well-developed
pubis and ossified epipodials, suggests that neither taxon
metamorphosed nor were they neotenic in the sense of branchiosaurids
and salamanders. Morphogenetic patterns in the foot suggest that digit
5 was developmentally delayed and the final digit to ossify in M.
pelikani and H. longicostatum. Overall patterns of postcranial
ossification may indicate postaxial dominance in limb and digit
formation, but also more developmental variation in early tetrapods
than has been appreciated. The phylogenetic position and developmental
patterns of M. pelikani and H. longicostatum are congruent with the
hypothesis that early tetrapods lacked metamorphosis ancestrally and
that stem-amniotes exhibited derived features of development, such as
rapid and complete ossification of the skeleton, potentially prior to
the evolution of the amniotic egg.
D. Angst, R. Amiot, E. Buffetaut, F. Fourel, F. Martineau, N.
Lazzerini & C. Lécuyer (2015)
Diet and climatic context of giant birds inferred from δ13Cc and δ18Oc
values of Late Paleocene and Early Eocene eggshells from southern
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
Tertiary eggshells from southeastern France are referred to the giant
δ13C values are interpreted as reflecting an herbivorous diet for these birds
δ13C values indicate a dry climate
δ18O values indicate a warm climate
Abundant fragments from eggs laid by giant birds occur in the
Paleocene (Thanetian) and Eocene (Sparnacian) sedimentary deposits of
southeastern France. In the Sparnacian, thick eggshell fragments,
assigned to the oospecies Ornitholithus arcuatus, correspond to very
large bird eggs that were most likely laid by Gastornis. The Thanetian
thin eggshell fragments, assigned to Ornitholithus biroi, were
presumably laid by a smaller, yet unidentified bird. In order to
investigate ecology and environment of these egg-laying birds, stable
carbon and oxygen isotope compositions of 125 fossil eggshell
fragments were analyzed. After removing samples affected by diagenetic
alteration of the calcitic shells, the measured range of δ13Cc values
(-11‰ to -6‰ V-PDB) is interpreted as reflecting an herbivorous diet
for these birds in a context of limited annual precipitation (≈ 500
mm.y-1). Stable oxygen isotope analysis of living ostrich eggshell
calcite, along with that of the water extracted from their albumen and
yolk, provided evidence to calculate isotopic fractionation factors
between both calcite and body water (αcalcite-body water = 1.03041)
and between body water and meteoric water (αbw-mw = 1.00399), using
δ18O values of local meteoric waters identified as the source of the
birds drinking water. Combined with the δ18O values of fossil
eggshells, both isotopic fractionations provided calculated δ18O
values of meteoric waters in the range -9.5‰ to -2.8‰ (V-SMOW) for the
Thanetian, and in the range -8.9‰ to -1.7‰ (V-SMOW) for the
Sparnatian. These large isotopic ranges likely reflect inter-annual
temperature variations of the complete year, suggesting a year round
egg-laying strategy. Corresponding Mean Air Temperatures (MAT) were
comprised between 20±4°C and 22±4°C during the Thanetian, and between
23±3°C and 25±3°C during the Sparnacian. These giant birds likely
lived under a warm and dry climate similar to that prevailing today in
western Mediterranean islands.
Armand de Ricqlès, Estelle Bourdon, Lucas J. Legendre & Jorge Cubo (2015)
Preliminary assessment of bone histology in the extinct elephant bird
Aepyornis (Aves, Palaeognathae) from Madagascar.
Comptes Rendus Palevol (advance online publication)
Aepyornis, a giant subfossil ratite from Madagascar, shows a
well-preserved bone histology. Hindlimb bones exhibit an extensive
histodiversity; the cortex is initially made of fibrolamellar,
well-vascularized primary bone that modulates locally into plexiform
or laminar patterns. Lines of arrested growth are generally weakly
expressed. Haversian reconstruction can be complete. Perimedullar
endosteal deposition is variable but can be extensive. The complex
causality (phylogenetic, systematic, ontogenetic and functional…
factors) involved in the production of the observed data is discussed.
B. F. Simões, F. L. Sampaio, C. Jared, M. M. Antoniazzi, E. R. Loew,
J. K. Bowmaker, A. Rodriguez, N. S. Hart, D. M. Hunt, J. C. Partridge
and D. J. Gower (2015)
Visual system evolution and the nature of the ancestral snake.
Journal of Evolutionary Biology (advance online publication)
The dominant hypothesis for the evolutionary origin of snakes from
‘lizards’ (non-snake squamates) is that stem snakes acquired many
snake features while passing through a profound burrowing (fossorial)
phase. To investigate this, we examined the visual pigments and their
encoding opsin genes in a range of squamate reptiles, focusing on
fossorial lizards and snakes. We sequenced opsin transcripts isolated
from retinal cDNA and used microspectrophotometry to measure directly
the spectral absorbance of the photoreceptor visual pigments in a
subset of samples. In snakes, but not lizards, dedicated fossoriality
(as in Scolecophidia and the alethinophidian Anilius scytale)
corresponds with loss of all visual opsins other than RH1 (λmax
490–497 nm); all other snakes (including less dedicated burrowers)
also have functional sws1 and lws opsin genes. In contrast, the
retinas of all lizards sampled, even highly fossorial amphisbaenians
with reduced eyes, express functional lws, sws1, sws2 and rh1 genes,
and most also express rh2 (i.e. they express all five of the visual
opsin genes present in the ancestral vertebrate). Our evidence of
visual pigment complements suggests that the visual system of stem
snakes was partly reduced, with two (RH2 and SWS2) of the ancestral
vertebrate visual pigments being eliminated, but that this did not
extend to the extreme additional loss of SWS1 and LWS that
subsequently occurred (probably independently) in highly fossorial
extant scolecophidians and A. scytale. We therefore consider it
unlikely that the ancestral snake was as fossorial as extant
scolecophidians, whether or not the latter are para- or monophyletic.
Molly F. Miller, Nichole E. Knepprath, David J. Cantrill, Jane E.
Francis & John L. Isbelle (2015)
Highly Productive Polar Forests from the Permian of Antarctica.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
74 in situ stumps occur in the Permian Buckley Fm, Beardmore Glacier
Record fossil forests thriving at ~ 75o S paleolatitude
Forests had large basal areas, high biomass, and estimated high
biomass added yr- 1 .
These Permian polar forests were as productive as most modern forests.
Two stratigraphically closely spaced bedding planes exposed at Lamping
Peak in the Upper Buckley Formation, Beardmore Glacier area,
Antarctica contain abundant in situ stumps (n=53, n=21) and other
plant fossils that allow reconstruction of forest structure and
biomass of Glossopteris forests that thrived at ~ 75o S paleolatitude
in the Permian. Mean trunk diameter is 14 and 25 cm, corresponding to
estimated mean maximum heights of 12 and 19 m. Basal areas are 65 and
80 m2ha- 1. The above ground biomass was calculated using allometric
equations for Ginkgo biloba, yielding biomasses of 147 and 178 Mg ha-
1. Biomass estimates based on comparison with biomass of modern
forests with equivalent basal areas are higher (225 – 400 Mg ha- 1).
The amount of above ground biomass added each year (Annual Net Primary
Productivity), based on biomass estimates and growth rings in
silicified plant material from the Buckley Formation nearby, is poorly
constrained, ranging from ~ 100 – 2000 g m- 2 yr- 1.
Compared to modern forests at all latitudes, the Permian forests have
high basal areas and high biomass, exceeded in both only by forests of
the U.S. Pacific northwest and Sequoia forests. The estimated range of
productivity (ANPP) is within that of many very productive modern
forests. The Lamping Peak forests’ basal areas and calculated biomass
are also larger than younger high paleolatitude fossil forests except
for Arctic Cenozoic forests.
Presence of these highly productive fossil forests at high
paleolatitude is consistent with hothouse conditions during the Late
Permian, prior to the eruption of the Siberian flood basalts.