[dinosaur] Bioerosion on vertebrate remains from Hateg Basin + crocodylomorph cranial shape evolution

Ben Creisler
[email protected]

Some recent papers:


Felix J. Augustin, Andreas T. Matzke, Zoltán Csiki-Sava & Hans-Ulrich
Pfretzschner (2019)
Bioerosion on vertebrate remains from the Upper Cretaceous of the Hateg
Basin, Romania and its taphonomic implications.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online
publication)
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1016_j.palaeo.2019.109318&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=nyVYqXfvR6gdrSnh1zwcagkCOJv2F2WX3k0XzxvyaDY&s=Rzfd9F8TdEFucWLDiJUX6UqDuJY1aHzzGg2cETLMbqU&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.sciencedirect.com_science_article_pii_S0031018219304869&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=nyVYqXfvR6gdrSnh1zwcagkCOJv2F2WX3k0XzxvyaDY&s=pIDqhPXdb6sTyGTl-MIzIYWDattYWf6dfF0nz0wvAJ8&e= 


Highlights

Trace fossils on bones are reported from the Upper Cretaceous of the Haţeg
Basin.
Most of the bioerosional traces are indicative of feeding behaviour.
The tracemakers are: termites, beetles, multituberculates, archosaurs and
plants.
Association of different traces allows the reconstruction of the taphonomy.
Scavenging and death of the vertebrates occurred on drylands in a fluvial
system.

Abstract

Bioerosion on fossil bones offers significant insights into both trophic
relationships of ancient ecosystems and vertebrate taphonomy. Here we
report six distinct trace fossil categories identified on isolated turtle,
crocodyliform and dinosaur remains from the Upper Cretaceous Sînpetru
Formation of the Haţeg Basin (Romania), for which five different probable
tracemakers are identified: (1) termites, (2) dermestid beetles, (3)
multituberculate mammals, (4) ziphodont theropod dinosaurs or
crocodyliforms, and (5) plants. This extraordinary diversity of
bioerosional trace fossils on vertebrate remains reveals insect-vertebrate
as well as vertebrate-vertebrate interactions previously undocumented in
the continental uppermost Cretaceous of Romania. The association between
different traces, especially since many of these are superimposed on top of
each other, allows the reconstruction of the detailed taphonomic history of
the specimens, indicating four different taphonomic pathways. The
vertebrate remains with trace fossils described here were most likely
exposed to post-mortem biotic interactions for a prolonged time period
before they were transported and/or trampled and finally buried. In the
palaeoenvironmental context of a heterogeneous braided river system with
low-lying wetlands and more elevated drylands, the death of the vertebrates
as well as the scavenging likely occurred on the drylands.


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Free pdf:

Pedro Lorena Godoy (2019)
Crocodylomorph cranial shape evolution and its relationship with body size
and ecology.
BioRxiv (preprint)
doi: https://urldefense.proofpoint.com/v2/url?u=http-3A__dx.doi.org_10.1101_724609&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=nyVYqXfvR6gdrSnh1zwcagkCOJv2F2WX3k0XzxvyaDY&s=eL_vCp_xqOmqFzX6l1DmHq2JzEcpIqVwUFhweEXI4ig&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.biorxiv.org_content_10.1101_724609v1&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=nyVYqXfvR6gdrSnh1zwcagkCOJv2F2WX3k0XzxvyaDY&s=J62kBI5UkX8OFzl-0Hg4UaspRdLlqP5i6SpMwExIJNI&e= 


Crocodylomorpha, which includes living crocodylians and their extinct
relatives, has a rich fossil record, extending back for more than 200
million years. Unlike modern semi-aquatic crocodylians, extinct
crocodylomorphs exhibited more varied lifestyles, ranging from marine to
fully terrestrial forms. This ecological diversity was mirrored by a
remarkable morphological disparity, particularly in terms of cranial
morphology, which seems to be closely associated with ecological roles in
the group. Here, I use geometric morphometrics to comprehensively
investigate cranial shape variation and disparity in Crocodylomorpha. I
quantitatively assess the relationship between cranial shape and ecology
(i.e. terrestrial, aquatic, and semi-aquatic lifestyles), as well as
possible allometric shape changes. I also characterise patterns of cranial
shape evolution and identify regime shifts. I found a strong link between
shape and size, and a significant influence of ecology on the observed
shape variation. Terrestrial taxa, particularly notosuchians, have
significantly higher disparity, and shifts to more longirostrine regimes
are associated with large-bodied aquatic or semi-aquatic species. This
demonstrates an intricate relationship between cranial shape, body size and
lifestyle in crocodylomorph evolutionary history. Additionally,
disparity-through-time analyses were highly sensitive to different
phylogenetic hypotheses, suggesting the description of overall patterns
among distinct trees. For crocodylomorphs, most results agree in an early
peak during the Early Jurassic and another in the middle of the Cretaceous,
followed by nearly continuous decline until today. Since only crown-group
members survived through the Cenozoic, this decrease in disparity was
likely the result of habitat loss, which narrowed down the range of
crocodylomorph lifestyles.

===

Nicholas M. A. Crouch, Vincent M. Lynch & Julia A. Clarke (2019)
A re-evaluation of the chemical composition of avian urinary excreta.
Journal of Ornithology (advance online publication)
DOI: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1007_s10336-2D019-2D01692-2D5&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=nyVYqXfvR6gdrSnh1zwcagkCOJv2F2WX3k0XzxvyaDY&s=_8eytGZ05ltK-BjdVoiMPlnCd7SFCLSqfLGbTWYG6lo&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__link.springer.com_article_10.1007_s10336-2D019-2D01692-2D5&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=nyVYqXfvR6gdrSnh1zwcagkCOJv2F2WX3k0XzxvyaDY&s=DqU7M4-z9vA2xTqMiCPIX9AfBTLevm36zmGQhgyIdt8&e= 


Osmoregulation in birds is complicated, with different organs acting
concurrently to regulate this physiological process. Of particular interest
is how the urinary excretions of birds can remove excess nitrogen while
minimizing the need for dietary water and balancing the physiological
demands of oviparity. It has long been concluded from chemical analyses,
and more recently from genetic studies, that uric acid is the principal
constituent of urine in Aves. However, research has also demonstrated that
waste material may be modified in the ceca immediately prior to it being
expelled. Here, we quantify the chemical composition of the urine component
of excreta of six avian species using X-ray diffraction techniques to test
the hypothesis that it is principally composed of uric acid, as commonly
reported. None of the analyzed samples were found to contain uric acid.
Instead, a variety of compounds including ammonium urate, struvite
(magnesium ammonium phosphate), and two unknown compounds, were found. Our
results show that the uric acid pathway is indeed the system by which
nitrogen is removed in these birds, but that additional modification occurs
in the urine prior to excretion. These results raise questions for future
research on the urinary excretions of birds, including identification of
the unknown compounds found in the present study.

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