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

Tinamou evolution + monotreme origin + turtle shoulders and shells



Ben Creisler
bcreisler@gmail.com

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

Sara Bertelli, Luis M. Chiappe and Gerald Mayr (2014)
Phylogenetic interrelationships of living and extinct Tinamidae,
volant palaeognathous birds from the New World.
Zoological Journal of the Linnean Society (advance online publication)
DOI: 10.1111/zoj.12156
http://onlinelibrary.wiley.com/doi/10.1111/zoj.12156/abstract



Tinamous, one of the earliest diverging living avian lineages,
consists of a Neotropical clade of palaeognathous birds with a fossil
record limited to the early Miocene–Quaternary of southern South
America. Here, we conduct a comprehensive, morphology-based
phylogenetic study of the interrelationships among extinct and living
species of tinamous. Morphological data of fossil species are included
in a matrix of 157 osteological and myological characters of 56
terminal taxa. The monophyly of most recognized genera is supported by
the results of the analysis. The cladistic analysis also recovers the
traditional subdivision between those tinamous specialized for open
areas (Nothurinae) and those inhabiting forested environments
(Tinaminae). Temporal calibration of the resultant phylogeny indicates
that such a basal divergence had already taken place in the early
Miocene, some 17 million years ago. The placement of the fossil
species within the open-area (Nothurinae) and the forest-dwelling
(Tinaminae) tinamous is also consistent with the palaeoenvironmental
conditions inferred from the associated fauna.


====

A. O. Averianov & A. V. Lopatin (2014)
On the phylogenetic position of monotremes (Mammalia, Monotremata).
Paleontological Journal 48(4): 426-446
DOI: 10.1134/S0031030114040042
http://link.springer.com/article/10.1134/S0031030114040042


Henosferida from the Middle-Upper Jurassic of Western Gondwana is the
most probable sister group for monotremes. They share the derived
pretribosphenic structure of lower molars combined with the presumably
absent protocone on the upper molars and the plesiomorphic retention
of postdentary bones and pseudangular process of the lower jaw. In
addition, the two groups share the dental formula with three molars
and the position of the Meckel’s groove, which passes ventral to the
mandibular foramen. In the course of subsequent evolution, monotremes
acquired the mammalian middle ear with three auditory ossicles
independently of therian mammals and multituberculates. Jurassic
Laurasian Shuotheriidae are probably a sister group of the Gondwanian
clade Henosferida + Monotremata. The Jurassic shuotheriid Pseudotribos
shows a great plesiomorphic similarity to monotremes in the structure
of the pectoral girdle, with a large interclavicle immovably connected
to the clavicle. In the lineages leading to therian mammals and
multituberculates, the pectoral girdle changed probably independently
and in parallel in connection with the establishment of the
parasagittal posture of the forelimbs (reduction of the interclavicle,
mobile articulation of the interclavicle with clavicle, reduction of
the procoracoid, and development of a supraspinous fossa of the
scapula) and formation of the mammalian middle ear with three auditory
ossicles.

==


Big buzz about a forthcoming paper on the origin of turtles... In the
meantime, a couple of recent papers:

Jacqueline E. Moustakas-Verho, Roland Zimm, Judith Cebra-Thomas, Netta
K. Lempiäinen, Aki Kallonen, Katherine L. Mitchell, Keijo Hämäläinen,
Isaac Salazar-Ciudad, Jukka Jernvall and Scott F. Gilbert (2014)
The origin and loss of periodic patterning in the turtle shell.
Development 141: 3033-3039
doi: 10.1242/dev.109041
http://dev.biologists.org/content/141/15/3033.abstract


The origin of the turtle shell over 200 million years ago greatly
modified the amniote body plan, and the morphological plasticity of
the shell has promoted the adaptive radiation of turtles. The shell,
comprising a dorsal carapace and a ventral plastron, is a layered
structure formed by basal endochondral axial skeletal elements (ribs,
vertebrae) and plates of bone, which are overlain by keratinous
ectodermal scutes. Studies of turtle development have mostly focused
on the bones of the shell; however, the genetic regulation of the
epidermal scutes has not been investigated. Here, we show that scutes
develop from an array of patterned placodes and that these placodes
are absent from a soft-shelled turtle in which scutes were lost
secondarily. Experimentally inhibiting Shh, Bmp or Fgf signaling
results in the disruption of the placodal pattern. Finally, a
computational model is used to show how two coupled reaction-diffusion
systems reproduce both natural and abnormal variation in turtle
scutes. Taken together, these placodal signaling centers are likely to
represent developmental modules that are responsible for the evolution
of scutes in turtles, and the regulation of these centers has allowed
for the diversification of the turtle shell.
==

Hiroshi Nagashima, Fumiaki Sugahara, Masaki Takechi, Noboru Sato and
Shigeru Kuratani (2014)
On the homology of the shoulder girdle in turtles.
Journal of Experimental Zoology Part B: Molecular and Developmental
Evolution (advance online publication)
DOI: 10.1002/jez.b.22584
http://onlinelibrary.wiley.com/doi/10.1002/jez.b.22584/abstract


The shoulder girdle in turtles is encapsulated in the shell and has a
triradiate morphology. Due to its unique configuration among amniotes,
many theories have been proposed about the skeletal identities of the
projections for the past two centuries. Although the dorsal ramus
represents the scapular blade, the ventral two rami remain uncertain.
In particular, the ventrorostral process has been compared to a
clavicle, an acromion, and a procoracoid based on its morphology, its
connectivity to the rest of the skeleton and to muscles, as well as
with its ossification center, cell lineage, and gene expression. In
making these comparisons, the shoulder girdle skeleton of anurans has
often been used as a reference. This review traces the history of the
debate on the homology of the shoulder girdle in turtles. And based on
the integrative aspects of developmental biology, comparative
morphology, and paleontology, we suggest acromion and procoracoid
identities for the two ventral processes.

===

Other stuff:


Luiz Carlos Borges Ribeiro, Ismar de Souza Carvalho & Francisco Macedo
Neto (2014)
Geopark Uberaba: Relevance of the Geological Heritage.
Geoheritage (advance online publication)
DOI: 10.1007/s12371-014-0131-y
http://link.springer.com/article/10.1007/s12371-014-0131-y




The Uberaba region (Minas Gerais, Brazil) has become famous for its
significant paleontological investigation, which has been conducted
there since the mid 1940s. Several taxa, especially of vertebrates,
unique in the paleobiological record, come from its fossiliferous
outcrops, associated with Uberaba and Marília formations (Bauru
Basin). Among these, the dinosaurs are especially important, as they
are exceptionally well preserved and diversified, allowing the
description of several species and consolidating Uberaba as the Land
of Brazilian Dinosaurs. The establishment, in 1991, of the
Paleontological Research Center Llewellyn Ivor Price and Dinosaur
Museum, in the neighborhood of Peirópolis, allowed the establishment
of research and educational actions to the preservation of the
geological heritage that transformed the local conditions through
geotourism. Besides the fossiliferous content, the diverse geosites
also comprise the important moments of the geological history, making
them extremely relevant places of the geological heritage, in
accordance with what is expected from a geopark. In 2010, the
Paleontological Research Center L.I. Price and the Dinosaur Museum
became part of the Cultural and Scientific Complex of Peirópolis of
the Federal University of Triângulo Mineiro. The Geopark Uberaba–Land
of Brazilian Dinosaurs was created in that same year, prompted by the
Geopark Project of the Geological Service of Brazil. The integration
of the geological heritage to the historical and cultural attributes
of national significance allowed the building of a unique identity for
this territory. Nowadays, in Uberaba, fossils are no longer limited to
scientific knowledge; they symbolize the socioeconomic and
environmental development tools, which are allowing the sustainable
regional development.

===