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Hyperodapedon (Archosauromorpha, Rhynchosauria) bone growth + non-dino papers

Ben Creisler@gmail.com

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

Debarati Mukherjee (2015)
New insights from bone microanatomy of the Late Triassic Hyperodapedon
(Archosauromorpha, Rhynchosauria): implications for archosauromorph
growth strategy.
Palaeontology (advance online publication)
DOI: 10.1111/pala.12146

Bone microanatomy of multiple postcranial skeletal elements of several
individuals of Hyperodapedon collected from India is reported. This
reveals that fibrolamellar bone tissue is predominant in the mid- and
inner cortices, whereas the peripheral region of the cortex is
composed of either parallel-fibred and/or lamellar bone. The pattern
of primary osteons mostly ranges between laminar and subplexiform.
Such predominance of fibrolamellar bone tissue in the cortex suggests
an overall fast growth, which slowed down considerably later in
ontogeny. Four distinct ontogenetic stages are identified based on the
bone microstructure. During the juvenile stage, growth was fast and
continuous, but it became punctuated during the early and late
sub-adult stages. In adult individuals, growth was slow and showed
periodic interruption but did not stop completely, suggesting that
Hyperodapedon had an indeterminate growth strategy. Interelemental
histovariations affecting cortical thickness, organization of the
vascular network, incidence of growth rings and extent of secondary
reconstruction are noted. Throughout ontogeny, the femora show higher
cortical thickness than humeri and tibiae, suggesting differential
appositional growth rate between the skeletal elements. Differences in
cortical thickness are noted in the ribs, which suggest differential
functional constraints based on anatomical site-specific occurrences.
Although fibrolamellar bone tissue became progressively more dominant
towards the archosaurs, there are considerable variations in the
growth patterns of the archosauromorphs. This is exemplified by the
bone microstructure of Hyperodapedon, which deviates from the
generalized slow-growth pattern proposed for all basal
archosauromorphs, suggesting that rapid growth was already present in
the archosauromorphs. The cortical thickness of various long bones of
Hyperodapedon bears similarity with that of several extant terrestrial
quadrupeds, suggesting that Hyperodapedon was essentially a
terrestrial quadruped.


Free pdf:

Colin Palmer & Mark T. Young (2015)
Surface drag reduction and flow separation control in pelagic
vertebrates, with implications for interpreting scale morphologies in
fossil taxa.
Royal Society Open Science. 2015 2:140163
DOI: 10.1098/rsos.140163

Living in water imposes severe constraints on the evolution of the
vertebrate body. As a result of these constraints, numerous extant and
extinct aquatic vertebrate groups evolved convergent osteological and
soft-tissue adaptations. However, one important suite of adaptations
is still poorly understood: dermal cover morphologies and how they
influence surface fluid dynamics. This is especially true for fossil
aquatic vertebrates where the soft tissue of the dermis is rarely
preserved. Recent studies have suggested that the keeled scales of
mosasaurids (pelagic lizards that lived during the Late Cretaceous)
aided in surface frictional drag reduction in a manner analogous to
the riblets on shark placoid scales. However, here we demonstrate that
mosasaurid scales were over an order of magnitude too large to have
this effect. More likely they increased the frictional drag of the
body and may have played a role in controlling flow separation by
acting as surface roughness that turbulated the boundary layer. Such a
role could have reduced pressure drag and enhanced manoeuvrability. We
caution those studying fossil aquatic vertebrates from positing the
presence of surface drag reducing morphologies, because as we show
herein, to be effective such features need to have a spacing of
approximately 0.1 mm or less.


Free pdf (text in French):

Brignon, A. (2014)
Les premières découvertes de crocodiliens fossiles dans la Pierre de
Caen (Bathonien, Normandie) au travers des archives de Georges Cuvier.
[The first discoveries of fossil crocodilians in the “Pierre de Caen”
(Bathonian, Normandy, France) through the archives of
Georges Cuvier. ]
Revue de Paléobiologie 33 (2) : 79-418

Unpublished manuscripts and iconographic documents in the archives of
Georges Cuvier provide new historical information about the discovery
of the first Jurassic reptiles in the Pierre de Caen Formation (Middle
Bathonian). These documents shed light on the beginnings of geology in
Calvados and on the oldest geological study of this area carried out
by Henry de Magneville before January 1821. In these early works, the
Banc bleu (Lower Bathonian) underlying the Pierre de Caen is confused
with the Marls of Dives and Villers-sur-Mer (Upper Callovian/Lower
Oxfordian). De la Beche who distinguished three bluish beds
established the correct position of the Pierre de Caen in 1822.
Unpublished documents attributable to Alexandre Brongniart, Constant
Prévost, Alexander von Humboldt and Cuvier reveal different
assumptions about the relative ages of the “Crocodiles of Caen”, “of
Honfleur” (Vaches-Noires) and of “le Havre”. A document by Félix
Lamouroux also presents a chronological list of the first discoveries
of crocodilians in the Pierre de Caen. As early as 1767, fossil
reptiles from Dives were reported in the Natural History Cabinet of
the Spanish Pedro Franco Davila. Lamouroux indicates that the first
crocodilian found in Caen was discovered around 1790. The unpublished
documents from the archives of Cuvier allow to trace the history of
the discovery of two iconic thalattosuchians from the Caen Stone : the
first specimen of Teleosaurus cadomensis, first named Crocodilus
cribratus by Lamouroux, from the quarries of Allemagne
(Fleury-sur-Orne) and the first specimen of Steneosaurus
megistorhynchus from the quarries of Quilly. Letters of Henry de
Magneville and Félix Lamouroux also highlight their relationship with
Cuvier. Lamouroux, sending to Cuvier most of the crocodilian remains
that he acquired, was much more faithful to his former teacher and
protector than to the interests of the city of Caen. Henry de
Magneville, the prefect of Calvados and the mayor of Caen wanted to
keep these findings for the museum of Caen, while trying to satisfy
Cuvier by sending him plaster replicas of these fossils. Finally,
Cuvier’s archives reveal unrecorded contributions by many
personalities of that time.


Gerald Mayr (2015)
Variations in the hypotarsus morphology of birds and their
evolutionary significance.
ACTA ZOOLOGICA (advance online publication)
DOI: 10.1111/azo.12117

Crown group (neornithine birds) exhibit a great variation in the
morphology of the hypotarsus, a structure on the proximal end of the
tarsometatarsus, which guides the tendons of the flexor muscles of the
toes. Hypotarsus morphology is of significance for the identification
of fossil taxa, and several extant groups show characteristic patterns
that are of phylogenetic interest. So far, however, the diversity of
hypotarsus morphologies has been little studied, and there are no
comprehensive studies across all neornithine birds. In particular, the
identities of the involved canals and sulci remain elusive, and some
confusion exists about their correct homologies. In this study,
hypotarsus morphologies are for the first time surveyed among all
extant birds, and basic patterns are characterized. Instances are
identified, in which particular hypotarsus morphologies are correlated
with certain locomotion types, inferences are made about possible
ancestral morphologies, and some patterns of phylogenetic interest are

A revised version of a paper that appeared earlier in MS form online:

Ashley M. Heers  and Kenneth P. Dial (2015)
Wings versus legs in the avian bauplan: Development and evolution of
alternative locomotor strategies.
Evolution (advance online publication)
DOI: 10.1111/evo.12576

Wings have long been regarded as a hallmark of evolutionary
innovation, allowing insects, birds, and bats to radiate into aerial
environments. For many groups, our intuitive and colloquial
perspective is that wings function for aerial activities, and legs for
terrestrial, in a relatively independent manner. However, insects and
birds often engage their wings and legs cooperatively. In addition,
the degree of autonomy between wings and legs may be constrained by
tradeoffs, between allocating resources to wings versus legs during
development, or between wing versus leg investment and performance
(because legs must be carried as baggage by wings during flight and
vice versa). Such tradeoffs would profoundly affect the development
and evolution of locomotor strategies, and many related aspects of
animal ecology. Here, we provide the first evaluation of wing versus
leg investment, performance and relative use, in birds—both across
species, and during ontogeny in three precocial species with different
ecologies. Our results suggest that tradeoffs between wing and leg
modules help shape ontogenetic and evolutionary trajectories, but can
be offset by recruiting modules cooperatively. These findings offer a
new paradigm for exploring locomotor strategies of flying organisms
and their extinct precursors, and thereby elucidating some of the most
spectacular diversity in animal history.


Zhao, T., Mayr, G., Wang, M. & Wang, W (2015)
A trogon-like arboreal bird from the early Eocene of China.
Alcheringa (advance online publication)
39, xxx–xxx. ISSN 0311-5518

We describe a partial skeleton of a new arboreal bird, Foshanornis
songi gen. et sp. nov., from the early Eocene Buxin Formation of
Guangdong, China. The new species shows some overall resemblances to
trogons (Trogoniformes) and also potentially exhibits an incipiently
heterodactyl foot. However, several key traits are distinct from
trogons, especially the morphology of the distal tarsometatarsus.
Irrespective of its phylogenetic affinities, the new fossil is the
first record of an arboreal bird from the Paleogene of China, and Asia
in general.