Note on the preservation of a limpet in living position from the Late Cretaceous, Seymour Island, Antarctica

1990 ◽  
Vol 64 (3) ◽  
pp. 477-478 ◽  
Author(s):  
William J. Zinsmeister
Keyword(s):  
Late Cretaceous ◽  
Life Style ◽  
Fossil Record ◽  
A Site ◽  
Seymour Island

Although limpets are fairly common in shelly deposits, there are no reports of limpets preserved in the living position from the fossil record. The life style of capped-shaped limpet gastropods almost precludes preservation in a living position. Herbivorous alga-feeding limpets live attached to a firm surface. The surfaces of attachment vary widely from rocky surfaces, shells, or seaweed. Upon death the shells become detached and are incorporated in the nearby sediments or are transported to a site of final deposition.

scholarly journals Confidence intervals for the duration of a mass extinction

Paleobiology ◽  
2012 ◽  
Vol 38 (2) ◽  
pp. 265-277 ◽  
Author(s):  
Steve C. Wang ◽  
Aaron E. Zimmerman ◽  
Brendan S. McVeigh ◽  
Philip J. Everson ◽  
Heidi Wong
Keyword(s):  
Confidence Interval ◽  
Confidence Intervals ◽  
Late Cretaceous ◽  
Mass Extinction ◽  
Fossil Record ◽  
Mass Extinctions ◽  
Late Permian ◽  
Stratigraphic Section ◽  
Stratigraphic Thickness ◽  
Seymour Island

A key question in studies of mass extinctions is whether the extinction was a sudden or gradual event. This question may be addressed by examining the locations of fossil occurrences in a stratigraphic section. However, the fossil record can be consistent with both sudden and gradual extinctions. Rather than being limited to rejecting or not rejecting a particular scenario, ideally we should estimate therangeof extinction scenarios that is consistent with the fossil record. In other words, rather than testing the simplified distinction of “sudden versus gradual,” we should be asking, “How gradual?”In this paper we answer the question “How gradual could the extinction have been?” by developing a confidence interval for the duration of a mass extinction. We define the duration of the extinction as the time or stratigraphic thickness between the first and last taxon to go extinct, which we denote by Δ. For example, we would like to be able to say with 90% confidence that the extinction took place over a duration of 0.3 to 1.1 million years, or 24 to 57 meters of stratigraphic thickness. Our method does not deny the possibility of a truly simultaneous extinction; rather, in this framework, a simultaneous extinction is one whose value of Δ is equal to zero years or meters.We present an algorithm to derive such estimates and show that it produces valid confidence intervals. We illustrate its use with data from Late Permian ostracodes from Meishan, China, and Late Cretaceous ammonites from Seymour Island, Antarctica.

Maastrichtian representatives of the dragonfly family Aeschnidiidae question the entomofaunal turnover of the early Late Cretaceous

2021 ◽  
Vol 4 (3) ◽  
Author(s):  
ANDRÉ NEL
Keyword(s):  
Late Cretaceous ◽  
Aquatic Insects ◽  
Fossil Record ◽  
Current Knowledge ◽  
Alternative Scenario ◽  
Family Level ◽  
Early Late ◽  
Freshwater Environments

Gaps in the fossil record are the major challenge for estimations of impacts of crises of biodiversity of the various clades. They can lead to important misinterpretations in the effects of the different events on the fauna and flora. It is especially the case for the end-Cretaceous, which is ‘near the midpoint of a 16-million-year gap in the insect fossil record’ (Schachat & Labandeira, 2021: 111). All the important Cretaceous insect Konzentrat Lagerstätten are before the Turonian. The analysis of Schachat et al. (2019) has reconstructed a massive loss of family-level diversity for the insects at the boundary Cretaceous-Cenozoic, a possible artefact due to this gap. An alternative scenario was that a turnover in the entomofauna occurred during the early Late Cretaceous in relation to the floristic changes of the Albian–Cenomanian (Nel et al., 2018). This turnover would have also affected the aquatic insects through important changes in the freshwater environments (Sinitshenkova & Zherikhin, 1996; Ivanov & Sukatsheva, 2002). The current knowledge on the odonatan fossil record suggests a pronounced turnover with the last records of several major clades during the Cenomanian-Turonian and first records of several modern ones during the same period (Nel et al., 2015). The widespread and very diverse Jurassic-Cretaceous family Aeschnidiidae is among the best examples of such extinctions supposed to have occurred after the Cenomanian, because of the absence of any fossil in younger strata.

The Cretaceous and Paleocene pleurotomariid (Gastropoda: Vetigastropoda) fauna of Seymour Island, Antarctica

2009 ◽  
Vol 83 (5) ◽  
pp. 750-766 ◽  
Author(s):  
M. G. Harasewych ◽  
Anton Oleinik ◽  
William Zinsmeister
Keyword(s):  
Species Richness ◽  
New Zealand ◽  
South America ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Southern India ◽  
New Combination ◽  
The Family ◽  
The Status ◽  
Seymour Island

Leptomaria antipodensis and Leptomaria hickmanae are described from the Upper Cretaceous [Maastrichtian] Lopez de Bertodano Formation, Seymour Island, and represent the first Mesozoic records of the family Pleurotomariidae from Antarctica. Leptomaria stillwelli, L. seymourensis, Conotomaria sobralensis and C. bayeri, from the Paleocene [Danian], Sobral Formation, Seymour Island, are described as new. Leptomaria larseniana (Wilckens, 1911) new combination, also from the Sobral Formation, is redescribed based on better-preserved material. The limited diversity of the pleurotomariid fauna of Seymour Island is more similar to that of the Late Cretaceous faunas of Australia and New Zealand in terms of the number of genera and species, than to the older, more diverse faunas of South America, southern India, or northwestern Madagascar, supporting the status of the Weddelian Province as a distinct biogeographic unit. The increase in the species richness of this fauna during the Danian may be due to the final fragmentation of Gondwana during this period.

scholarly journals Hatching Asynchrony in Oviraptorid Dinosaurs Sheds Light on Their Unique Nesting Biology

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
T -R Yang ◽  
T Engler ◽  
J N Lallensack ◽  
A Samathi ◽  
M Makowska ◽  
...  
Keyword(s):  
Reproductive Biology ◽  
Late Cretaceous ◽  
Fossil Record ◽  
Research Topic ◽  
Hatching Asynchrony ◽  
Jiangxi Province ◽  
Nesting Biology ◽  
Tomographic Images ◽  
Communal Nesting ◽  
Nesting Behaviors

Synopsis Dinosaur nesting biology has been an intriguing research topic, though dinosaur behaviors were relatively less illuminated because of the constraints of the fossil record. For instance, hatching asynchrony, where eggs in a single clutch hatch at different times, is unique to modern neoavian birds but was also suggested to be present in oviraptorid dinosaurs based on a possible partial clutch of four embryo-containing eggs from Mongolia. Unfortunately, unequivocal evidence for the origination of these eggs from a single clutch is lacking. Here we report a new, better preserved partial oviraptorid clutch with three embryo-containing eggs—a single egg (Egg I) and a pair (Egg II/III)—from the Late Cretaceous Nanxiong Group of Jiangxi Province, China. Geopetal features indicate that the pair of eggs was laid prior to the single egg. Neutron tomographic images in combination with osteological features indicate that the embryo of the single egg is less developed than those of the paired eggs. Eggshell histology suggests that the embryo-induced erosion in the paired eggs is markedly more pronounced than in the single egg, providing a new line of evidence for hatching asynchrony. The inferred hatching asynchrony in combination with previously surmised thermoregulatory incubation and communal nesting behaviors very likely suggests that oviraptorid dinosaurs presented a unique reproductive biology lacking modern analogs, which is contrary to the predominant view that their reproductive biology was intermediate between that of modern crocodiles and birds.

CIRCULAR OR SPHERICAL VESSELS IN THE FOSSIL RECORD

IAWA Journal ◽  
2015 ◽  
Vol 36 (2) ◽  
pp. 152-157 ◽  
Author(s):  
Pieter Baas ◽  
Rashmi Srivastava ◽  
Steven R. Manchester ◽  
Elisabeth A. Wheeler
Keyword(s):  
Late Cretaceous ◽  
Fossil Record ◽  
Central India ◽  
Type Specimen ◽  
Axillary Buds ◽  
Before Present ◽  
Early Paleocene

Strangely configured vessels composed of few elements interconnected in a sphere- or ring-like structure are reported from the type specimen of Amooroxylon deccanensis Bande & Prakash, a large fossil trunk from the Deccan Intertrappean Beds of central India (late Cretaceous-early Paleocene, about 66 MY before present). In the recent flora, circular vessels have been found mainly in association with branching nodes, axillary buds, wound callus, and pathogens, and they have been artificially induced by auxin. The presence of circular vessels in this fossil trunk showing no signs of branching or trauma makes this record highly unusual.

Paleocene diversification of bucciniform gastropods on Seymour Island, Antarctica

1996 ◽  
Vol 70 (6) ◽  
pp. 923-934 ◽  
Author(s):  
Anton E. Oleinik ◽  
William J. Zinsmeister
Keyword(s):  
New Species ◽  
Mass Extinction ◽  
Fossil Record ◽  
New Genus ◽  
Shell Morphology ◽  
Geographic Isolation ◽  
Extinction Event ◽  
Early Paleocene ◽  
Mass Extinction Event ◽  
Seymour Island

Following the mass extinction event at the end of the Cretaceous, the marine molluscan faunas of the high southern latitudes underwent a marked period of diversification during the early Paleocene. The appearance of four new species belonging to the new genus Seymourosphaera, tentatively placed in the subfamily Pseudolivinae, from the lower Paleocene strata of Seymour Island, Antarctic Peninsula, clearly illustrates the post-Cretaceous extinction diversification. The abrupt radiation of the buccinids during the early Paleocene, was also apparently related to geographic isolation of Antarctica during final breakup of Gondwana. Comparative analysis of shell morphology of Seymourosphaera, new genus reveals close morphologic similarities, not only with taxa within Pseudolivinae, but also with several genera and subgenera belonging to the families Buccinidae and Nassariidae. However, incompleteness of the fossil record and a “generalized” shell morphology make difficult establishment of unequivocal phylogenetic relationships for Seymourosphaera. A taxonomic review of most closely related, and possibly ancestral genus Austrosphaera Camacho, 1949, is provided. The following new species of genus Seymourosphaera new genus are described: Seymourosphaera bulloides new species, S. subglobosa new species, S. depressa new species, and S. elevata new species.

scholarly journals A new Late Cretaceous iguanomorph from North America and the origin of New World Pleurodonta (Squamata, Iguania)

2017 ◽  
Vol 284 (1847) ◽  
pp. 20161902 ◽  
Author(s):  
David G. DeMar ◽  
Jack L. Conrad ◽  
Jason J. Head ◽  
David J. Varricchio ◽  
Gregory P. Wilson
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Fossil Record ◽  
New World ◽  
Cladistic Analysis ◽  
Arid Environment ◽  
New Taxon ◽  
Low Latitude ◽  
Anatomical Features ◽  
Parietal Foramen

Iguanomorpha (stem + crown Iguania) is a diverse squamate clade with members that predominate many modern American lizard ecosystems. However, the temporal and palaeobiogeographic origins of its constituent crown clades (e.g. Pleurodonta (basilisks, iguanas, and their relatives)) are poorly constrained, mainly due to a meagre Mesozoic-age fossil record. Here, we report on two nearly complete skeletons from the Late Cretaceous (Campanian) of North America that represent a new and relatively large-bodied and possibly herbivorous iguanomorph that inhabited a semi-arid environment. The new taxon exhibits a mosaic of anatomical features traditionally used in diagnosing Iguania and non-iguanian squamates (i.e. Scleroglossa; e.g. parietal foramen at the frontoparietal suture, astragalocalcaneal notch in the tibia, respectively). Our cladistic analysis of Squamata revealed a phylogenetic link between Campanian-age North American and East Asian stem iguanomorphs (i.e. the new taxon + Temujiniidae). These results and our evaluation of the squamate fossil record suggest that crown pleurodontans were restricted to the low-latitude Neotropics prior to their early Palaeogene first appearances in the mid-latitudes of North America.

Anatomy, systematics, paleoenvironment, growth, and age of the sauropod dinosaur Sonorasaurus thompsoni from the Cretaceous of Arizona, USA

2016 ◽  
Vol 90 (1) ◽  
pp. 102-132 ◽  
Author(s):  
Michael D. D’Emic ◽  
Brady Z. Foreman ◽  
Nathan A. Jud
Keyword(s):  
Life History ◽  
Late Cretaceous ◽  
North American ◽  
Phylogenetic Relationships ◽  
Fossil Record ◽  
Cladistic Analysis ◽  
Detrital Zircons ◽  
Bone Histology ◽  
Seasonal Precipitation ◽  
Adult Size

AbstractSauropod dinosaurs are rare in the Cretaceous North American fossil record in general and are absent from that record for most of the Late Cretaceous. Sonorasaurus thompsoni from the Turney Ranch Formation of the Bisbee Group of Arizona, USA, potentially represents one of the youngest sauropods before their ca. 30-million-year-long hiatus from the record. The anatomy of Sonorasaurus has only been briefly described, its taxonomic validity has been questioned, several hypotheses have been proposed regarding its phylogenetic relationships, and its life history, geologic age, and reported paleoenvironment are ambiguous.Herein we assess the systematics, paleoenvironment, life history, and geologic age of Sonorasaurus based on firsthand observation, bone histology, and fieldwork in the holotypic quarry and environs. The validity of S. thompsoni is substantiated by autapomorphies. Cladistic analysis firmly places it within the Brachiosauridae, in contrast to results of some recent analyses. Bone histology suggests that the only known exemplar of Sonorasaurus grew slowly and sporadically compared to other sauropods and was approaching its adult size. In contrast with previous assessments of a coastal/estuarine paleoenvironment for the Turney Ranch Formation, our sedimentological and plant macrofossil data indicate that Sonorasaurus lived in a semiarid, low relief evergreen woodland that received highly variable (perhaps seasonal) precipitation. We obtained detrital zircons from the holotypic quarry for U-Pb dating, which only yielded Barremian-aged and older grains, whereas other radiometric and biostratigraphic data suggest that the sediments at the quarry were deposited near the Albian-Cenomanian boundary.Sonorasaurus is taxonomically valid, represents one of the geologically youngest brachiosaurid sauropods, and inhabited a harsh inland evergreen-dominated woodland environment that limited its growth. A review of other Bisbee Group dinosaurs suggests that its fauna, although poorly sampled, exhibits broad similarity to those from coeval North American horizons, reinforcing the apparent faunal homogeneity at the time.

The fossil record of Cunoniaceae: new evidence from Late Cretaceous wood of Antarctica?

2000 ◽  
Vol 111 (1-2) ◽  
pp. 127-144 ◽  
Author(s):  
Imogen Poole ◽  
David J. Cantrill ◽  
Peta Hayes ◽  
Jane Francis
Keyword(s):  
Late Cretaceous ◽  
Fossil Record ◽  
New Evidence
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