[dinosaur] Archosaur joint soft tissues + Karoo Basin vertebrate assemblage turnover + more

Ben Creisler
[email protected]

Some recent non-dino papers:


===

Henry P. Tsai,  Morgan L. Turner,  Armita R. Manafzadeh &  Stephen M.
Gatesy (2019)
Contrast‐enhanced XROMM reveals in vivo soft tissue interactions in the hip
of Alligator mississippiensis.
Journal of Anatomy (advance online publication)
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1111_joa.13101&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=KGjoR4LFgmTbuGXCZRCSgXidNV_uVi5CbfUWFSp0GLQ&s=EwFl1qTkeRDn-Oxr1gH0QuXb8Tz-1Ox38-OZzC3P7Lk&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__onlinelibrary.wiley.com_doi_10.1111_joa.13101&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=KGjoR4LFgmTbuGXCZRCSgXidNV_uVi5CbfUWFSp0GLQ&s=9nWFfsk_7uR-Hnlw6-kf3X18vFxdZytzO2MrVh1PHlY&e= 


Extant archosaurs exhibit highly divergent articular soft tissue anatomies
between avian and crocodilian lineages. However, the general lack of
understanding of the dynamic interactions among archosaur joint soft
tissues has hampered further inferences about the function and evolution of
these joints. Here we use contrast‐enhanced computed tomography to generate
3D surface models of the pelvis, femora, and hip joint soft tissues in an
extant archosaur, the American alligator. The hip joints were then animated
using marker‐based X‐Ray Reconstruction of Moving Morphology (XROMM) to
visualize soft tissue articulation during forward terrestrial locomotion.
We found that the anatomical femoral head of the alligator travels beyond
the cranial extent of the bony acetabulum and does not act as a central
pivot, as has been suggested for some extinct archosaurs. Additionally, the
fibrocartilaginous surfaces of the alligator’s antitrochanter and femoral
neck remain engaged during hip flexion and extension, similar to the
articulation between homologous structures in birds. Moreover, the femoral
insertion of the ligamentum capitis moves dorsoventrally against the
membrane‐bound portion of the medial acetabular wall, suggesting that the
inner acetabular foramen constrains the excursion of this ligament as it
undergoes cyclical stretching during the step cycle. Finally, the articular
surface of the femoral cartilage model interpenetrates with those of the
acetabular labrum and antitrochanter menisci; we interpret such
interpenetration as evidence of compressive deformation of the labrum and
of sliding movement of the menisci. Our data illustrate the utility of
XROMM for studying in vivo articular soft tissue interactions. These
results also allow us to propose functional hypotheses for crocodilian hip
joint soft tissues, expanding our knowledge of vertebrate connective tissue
biology and the role of joint soft tissues in locomotor behavior.

==

Robert A. Gastaldo, Johann Neveling, John W. Geissman & CindY V. Looy (2019)
Testing the Daptocephalus and Lystrosaurus assemblage zones in a
lithostratographic, magnetostratigraphic, and palynological framework in
the Free State, South Africa.
PALAIOS  34(11): 542-561
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.2110_palo.2019.019&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=KGjoR4LFgmTbuGXCZRCSgXidNV_uVi5CbfUWFSp0GLQ&s=8zFGQfzSy7a2mxjWqSv5F-ciTAY51uPuKxzvCJW_IXg&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__pubs.geoscienceworld.org_sepm_palaios_article-2Dabstract_34_11_542_574685_TESTING-2DTHE-2DDAPTOCEPHALUS-2DAND-2DLYSTROSAURUS&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=KGjoR4LFgmTbuGXCZRCSgXidNV_uVi5CbfUWFSp0GLQ&s=3pBDPi2BON2RIR-PnQbGtuaZuIn3vosGI1OT_JgKELw&e= 

The vertebrate-fossil record in the Karoo Basin has served as the accepted
model for how terrestrial ecosystems responded to the end-Permian
extinction event. A database of several hundred specimens, placed into
generalized stratigraphies, has formed the basis of a step-wise extinction
scenario interpreted by other workers as spanning the upper Daptocephalus
(=Dicynodon) to Lystrosaurus Assemblage Zones (AZ). Seventy-three percent
of specimens used to construct the published model originate from three
farms in the Free State: Bethel, Heldenmoed, and Donald 207 (Fairydale).
The current contribution empirically tests: (1) the stratigraphic
resolution of the vertebrate record on these farms; (2) whether a sharp
boundary exists that delimits the vertebrate assemblage zones in these
classic localities; and (3) if the Lystrosaurus AZ is of early Triassic
age. We have used a multi-disciplinary approach, combining
lithostratigraphy, magnetostratigraphy, vertebrate biostratigraphy, and
palynology, to test these long-held assumptions.

Previously reported vertebrate-collection sites have been physically placed
into a litho- and magnetostratigraphic framework on the Bethel and
Heldenmoed farms. The reported assemblage-zone boundary is used as the
datum against which the stratigraphic position of vertebrates is compared
and a preliminary magnetostratigraphy constructed. We find specimens of the
Daptocephalus AZ originate in the Lystrosaurus AZ (as currently defined)
and vice versa, and discrepancies between reported and field-checked
stratigraphic positions below or above the assemblage-zone boundary often
exceed 30 m. Hence, the utility of the data set in defining a sharp or
abrupt biozone boundary is questionable. We further demonstrate the
presence of a stratigraphically thick reverse polarity magnetozone that
encompasses the reported assemblage-zone boundary, implying that these
rocks are not correlative with the end-Permian event, which is reported to
lie in a normal polarity chron. A latest Permian age is supported by
palynological data from the Lystrosaurus AZ on the Donald 207 (Fairydale)
farm, with equivalence to Australian (APP602) and Eastern Cape Province
assemblages. We conclude that the turnover from the Daptocephalus to
Lystrosaurus Assemblage Zones is more protracted than envisioned, it is not
coincident with the end-Permian event as recognized in the marine realm,
and little evidence exists in support of a three-phased extinction model
based on vertebrate assemblages in the Karoo Basin.

====

A.D. Muscente,  Rowan C. Martindale, James D. Schiffbauer, Abby L.
Creighton & Brooke A. Bogan (2019)
Taphonomy of the Lower Jurassic Konservat-Lagerstätte at Ya Ha Tinda
(Alberta, Canada) and its significance for exceptional fossil preservation
during oceanic anoxic events.
PALAIOS (2019) 34 (11): 515-541.
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.2110_palo.2019.050&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=KGjoR4LFgmTbuGXCZRCSgXidNV_uVi5CbfUWFSp0GLQ&s=x6o36TRDdNmc6ph7pS4jyGhTB6DwjrYbCwaeq2WTH9w&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__pubs.geoscienceworld.org_sepm_palaios_article-2Dabstract_34_11_515_574686_TAPHONOMY-2DOF-2DTHE-2DLOWER-2DJURASSIC-2DKONSERVAT&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=KGjoR4LFgmTbuGXCZRCSgXidNV_uVi5CbfUWFSp0GLQ&s=72Y5SKdXoFAMFa_aOtsCzghznoAj8ogsEY3H2nYgzdo&e= 

Konservat-Lagerstätten provide the most complete snapshots of ancient
organisms and communities in the fossil record. In the Mesozoic, these
deposits are rarely found in marine facies outside Oceanic Anoxic Event
(OAE) intervals, suggesting that OAEs set the stage for exceptional fossil
preservation. Although anoxia does not guarantee survival of
non-biomineralized tissues or articulated skeletons, other OAE phenomena
may promote their conservation. Here, we test this hypothesis with a
taphonomic analysis of the Konservat-Lagerstätte in the black shales and
siltstones of the Jurassic Fernie Formation at Ya Ha Tinda (Alberta,
Canada). This deposit contains crustacean cuticles, coleoid gladii with ink
sacs and mantle tissues, and articulated skeletons of fish, crinoids, and
ichthyosaurs. The fossils were preserved in the Pliensbachian and Toarcian
(Early Jurassic) when euxinic conditions were common in the area, in part,
due to the ~183 Ma Toarcian OAE. Some of the fossils contain carbonaceous
material, but the majority consists of apatite minerals, and phosphatic
gladii demonstrate that some animals were preserved through secondary
phosphate mineralization. Phosphatization generally occurs within
phosphate-rich sediment, but oceanic anoxia causes sediment to release
phosphorus and prevents animals from colonizing seafloor habitats.
Accordingly, we propose that the animals were preserved during brief
episodes of bottom water oxia and/or dysoxia, when the environment would
have been most favorable to benthic communities and phosphate
mineralization. In this setting, phosphatization may have been fueled by
phosphate delivery from continental weathering in response to climatic
warming, ocean upwelling of eutrophic water, and/or nutrient trapping by
anoxia in the basin.

News:

https://urldefense.proofpoint.com/v2/url?u=https-3A__phys.org_news_2019-2D11-2Dexceptional-2Dfossils-2Dair.html&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=KGjoR4LFgmTbuGXCZRCSgXidNV_uVi5CbfUWFSp0GLQ&s=dLlk9kwtAx1URWzboRcgZWJLuLvSt1ems7Ar_3DLEGs&e= 
==


Free pdf:

Ruediger Stein (2019)
The late Mesozoic‐Cenozoic Arctic Ocean climate and sea ice history: A
challenge for past and future scientific ocean drilling.
Paleoceanography and Paleoclimatology (advance online publication)
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1029_2018PA003433&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=KGjoR4LFgmTbuGXCZRCSgXidNV_uVi5CbfUWFSp0GLQ&s=2D5BQox9TJq8YywLin6SYuUMf_5Q3nNMqpGg756_I64&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__agupubs.onlinelibrary.wiley.com_doi_10.1029_2018PA003433&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=KGjoR4LFgmTbuGXCZRCSgXidNV_uVi5CbfUWFSp0GLQ&s=Urx4vpfY0oxEghkzOjfOSjHz6dwewAQ95Q2wQCOc27w&e= 

Free pdf:
https://urldefense.proofpoint.com/v2/url?u=https-3A__agupubs.onlinelibrary.wiley.com_doi_pdf_10.1029_2018PA003433&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=KGjoR4LFgmTbuGXCZRCSgXidNV_uVi5CbfUWFSp0GLQ&s=c0M_xzBt_cGXOMgKXKXK0qGkTWBZ2jZeF3xm6-wRJRo&e= 


Over the past 3‐4 decades, coincident with global warming and atmospheric
CO2 increase, Arctic sea ice has significantly decreased in its extent as
well as in thickness. When extrapolating this alarming trend, the central
Arctic Ocean might become ice‐free during summers within about the next 2‐5
decades. Paleoclimate records allow us to better understand the processes
controlling modern climate change and distinguish between natural and
anthropogenic forcing. In this context, detailed studies of the earlier
Earth history characterized by a much warmer global climate with elevated
atmospheric CO2 concentrations are important. The main focus of this review
paper is the long‐term late Mesozoic‐Cenozoic Arctic Ocean climate history
from Greenhouse to Icehouse conditions, with special emphasis on Arctic sea
ice history. Starting with some information on the Cretaceous Arctic Ocean
climate, this paper will concentrate on selected results from IODP
Expedition 302 (ACEX), the first scientific drilling in the permanently
ice‐covered Arctic Ocean, dealing with the Cenozoic climate history. While
these results from ACEX were unprecedented, key questions related to the
Cenozoic Arctic climate history remain unanswered, largely due to the major
mid‐Cenozoic hiatus (if existing) and partly to the poor recovery of the
ACEX record. Following‐up ACEX and its cutting‐edge science, a second
scientific drilling on Lomonosov Ridge with a focus on the reconstruction
of the continuous and complete Cenozoic Arctic Ocean climate history, has
currently been proposed and scheduled as IODP Expedition 377 for 2021.


<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.avg.com_email-2Dsignature-3Futm-5Fmedium-3Demail-26utm-5Fsource-3Dlink-26utm-5Fcampaign-3Dsig-2Demail-26utm-5Fcontent-3Dwebmail&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=KGjoR4LFgmTbuGXCZRCSgXidNV_uVi5CbfUWFSp0GLQ&s=I84qVipTh8ALrCV4YKruM1Jv_CBSFqaVoppKhoN90X4&e= >
Virus-free.
www.avg.com
<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.avg.com_email-2Dsignature-3Futm-5Fmedium-3Demail-26utm-5Fsource-3Dlink-26utm-5Fcampaign-3Dsig-2Demail-26utm-5Fcontent-3Dwebmail&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=KGjoR4LFgmTbuGXCZRCSgXidNV_uVi5CbfUWFSp0GLQ&s=I84qVipTh8ALrCV4YKruM1Jv_CBSFqaVoppKhoN90X4&e= >
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>