scholarly journals A Giant Ostrich from the Lower Pleistocene Nihewan Formation of North China, with a Review of the Fossil Ostriches of China

Diversity ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 47
Author(s):  
Eric Buffetaut ◽  
Delphine Angst
Keyword(s):  
Geographical Distribution ◽  
Late Pleistocene ◽  
North China ◽  
Hebei Province ◽  
Early Pleistocene ◽  
Wide Geographical Distribution ◽  
Lower Pleistocene ◽  
The Crimea

A large incomplete ostrich femur from the Lower Pleistocene of North China, kept at the Muséum National d’Histoire Naturelle (Paris), is described. It was found by Father Emile Licent in 1925 in the Nihewan Formation (dated at about 1.8 Ma) of Hebei Province. On the basis of the minimum circumference of the shaft, a mass of 300 kg, twice that of a modern ostrich, was obtained. The bone is remarkably robust, more so than the femur of the more recent, Late Pleistocene, Struthio anderssoni from China, and resembles in that regard Pachystruthio Kretzoi, 1954, a genus known from the Lower Pleistocene of Hungary, Georgia and the Crimea, to which the Nihewan specimen is referred, as Pachystruthio indet. This find testifies to the wide geographical distribution of very massive ostriches in the Early Pleistocene of Eurasia. The giant ostrich from Nihewan was contemporaneous with the early hominins who inhabited that region in the Early Pleistocene.

Disentangling Astraea lobata: three new names in Astraea based on previous varieties of Croton lobatus (Euphorbiaceae)

Phytotaxa ◽  
2017 ◽  
Vol 317 (4) ◽  
pp. 297 ◽  
Author(s):  
OTÁVIO LUIS MARQUES DA SILVA ◽  
INÊS CORDEIRO
Keyword(s):  
Geographical Distribution ◽  
Geographic Distribution ◽  
Taxonomic Revision ◽  
Morphological Characters ◽  
Complex Species ◽  
Wide Geographical Distribution ◽  
As Species

Within Astraea Klotzsch (1841: 194), Astraea lobata (Linnaeus 1753: 1005) Klotzsch (1841: 194) may be considered the most taxonomically complex species due to its wide geographical distribution and the several varieties that have been proposed for this species by Müller Argoviensis (1866, 1874). In his concept, Müller Argoviensis (1866) united under Croton lobatus Linnaeus (1753: 1005) plants with 3–5-partite leaves almost as long as the petioles, subulate stipules, the bracts not well developed and ovaries with varied indumentum. In De Candolles’s Prodromus, Müller Argoviensis (1866) recognized eight varieties, maintaining this concept in the Flora Brasiliensis (Müller Argoviensis 1874) with few modifications. Morphological characters and geographical distribution support the recognition of some of these varieties as species distinct from A. lobata. As part of an undergoing taxonomic revision of Astraea, these distinct taxa must be validly published for further studies on this genus. Therefore, in this note we propose these novelties with commentaries about morphology and geographic distribution, along with photos to illustrate them and lectotypifications when necessary.

Emergence of critical climate states during the Pleistocene

2021 ◽  
Author(s):  
Nicholas Golledge
Keyword(s):  
Dynamical Systems ◽  
Late Pleistocene ◽  
Dominant Frequency ◽  
Climate System ◽  
Ice Age ◽  
Early Pleistocene ◽  
Glacial Cycles ◽  
Pleistocene Climate ◽  
System Nodes ◽  
Systems Framework

<p>During the Pleistocene (approximately 2.6 Ma to present) glacial to interglacial climate variability evolved from dominantly 40 kyr cyclicity (Early Pleistocene) to 100 kyr cyclicity (Late Pleistocene to present). Three aspects of this period remain poorly understood: Why did the dominant frequency of climate oscillation change, given that no major changes in orbital forcing occurred? Why are the longer glacial cycles of the Late Pleistocene characterised by a more asymmetric form with abrupt terminations? And how can the Late Pleistocene climate be controlled by 100 kyr cyclicity when astronomical forcings of this frequency are so much weaker than those operating on shorter periods? Here we show that the decreasing frequency and increasing asymmetry that characterise Late Pleistocene ice age cycles both emerge naturally in dynamical systems in response to increasing system complexity, with collapse events (terminations) occuring only once a critical state has been reached. Using insights from network theory we propose that evolution to a state of criticality involves progressive coupling between climate system 'nodes', which ultimately allows any component of the climate system to trigger a globally synchronous termination. We propose that the climate state is synchronised at the 100 kyr frequency, rather than at shorter periods, because eccentricity-driven insolation variability controls mean temperature change globally, whereas shorter-period astronomical forcings only affect the spatial pattern of thermal forcing and thus do not favour global synchronisation. This dynamical systems framework extends and complements existing theories by accomodating the differing mechanistic interpretations of previous studies without conflict.</p>

Geometric morphometric analysis of different species of Cyprideis deriving from the Early Pleistocene record of Greece.

2021 ◽  
Author(s):  
Ypermachia Dimitriou ◽  
Penelope Papadopoulou ◽  
Maria Kolendrianou ◽  
Maria Tsoni ◽  
George Iliopoulos
Keyword(s):  
Endemic Species ◽  
Early Pleistocene ◽  
Geometric Morphometric ◽  
Representative Species ◽  
Lower Pleistocene ◽  
Close Relationship ◽  
Outline Analysis ◽  
Geometric Morphometric Analysis ◽  
The Right ◽  
Of Greece

<p>The genus Cyprideis is one of the most widespread ostracod representative of the Pleistocene brackish palaeoenvironments. Especially <em>Cyprideis torosa </em>is often found in great numbers and even in monospecific taphocoenoses and for this reason its study is very useful for palaeoenvironmental reconstructions.  The identification of different species of Cyprideis is often complicated and needs careful morphology inspection. This becomes even more difficult in the case of endemic species which present significant similarities with each other.  In this work, we have studied and analyzed several  Cyprideis species (<em>C.torosa, C. frydaci, C.dictyoti, C. pannonica, C. elisabeta, C. seminulum, C. heterostigma</em>) deriving from brackish palaeoenvironments of a Lower Pleistocene marl sequence in Sousaki Basin (Northeastern Corinth Graben, Greece). More specifically size measurements and geometric morphometrics (lateral valve outline of both right and left valves as well as females and males) were used in order to attest the similarities and dissimilarities between the different species and draw conclusions about their origin.  According to the valve outline and the multivariate analysis a close relationship between the valve shape of all Cyprideis species can be noticed. <em>C. torosa</em> is commonly grouped with <em>C. pannonica</em> except in the male right valve where the two species show some differences.  The endemic species <em>C. frydaci</em> and <em>C. dictyoti</em> can be identified by the differences in the right valve of the male and female respectively.  The other species could not be substantially differentiated using just the outline analysis which possibly denotes their common genetic origin.  The valve outline has proved to be a very useful character for recognizing the different species especially when the two valves of both females and males are considered. More analyses of representative species of Miocene and Pliocene Cyprideis are needed in order to establish their phylogenetic relationships and draw conclusions about their common ancestor.</p>

scholarly journals Quaternary stratigraphy: Recent changes

2012 ◽  
Vol 92 (4) ◽  
pp. 1-16
Author(s):  
Tivadar Gaudenji ◽  
Mladjen Jovanovic
Keyword(s):  
Soviet Union ◽  
Oxygen Isotope ◽  
Former Soviet Union ◽  
Early Pleistocene ◽  
Stratigraphic Correlation ◽  
Global Context ◽  
Quaternary Stratigraphy ◽  
Stratigraphic Model ◽  
Stratigraphic Division ◽  
Lower Pleistocene

Corrections to the Quaternary stratigraphic division of Serbia was updated/renewed by lowering limit of the Pleistocene / Quaternary to the beginning of the Gelasian that is at approximately 2.588 million years. Rather than the officially rejected Penck & Br?ckner Alpine stratigraphic model, the use of oxygen isotope stages (OIS / MIS) is recommended. Climatostratigraphic terms glacial and interglacial have a regional applicability and their use is recommended only in areas where there are traces of glaciation, while the terms cold and warm stage (or moderate) stages should be used within the global context. Eopleistocene is a regional term for the former Soviet Union and due to its uniqueness it can hardly be applied in the stratigraphical scheme of the Quaternary depostis in Serbia. With the latest extension of the Lower Pleistocene, further use of Eopleistocene would lead to further confusion in stratigraphic correlation as such the use of the Lower / Early Pleistocene or other appropriate stratigraphic units is recommended.

scholarly journals New records of the fur seal Callorhinus (Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of Northern California and comments on otariid dental evolution

2018 ◽  
Author(s):  
Robert Boessenecker
Keyword(s):  
New Record ◽  
New Records ◽  
Size Range ◽  
Early Pleistocene ◽  
Callorhinus Ursinus ◽  
Northern California ◽  
Northeast Pacific ◽  
Fur Seal ◽  
Dental Evolution ◽  
Lower Pleistocene

New fossils representing two species of the fur seal Callorhinus are reported from the uppermost Pliocene to lower Pleistocene Rio Dell Formation of northern California. The finds include latest Pliocene–earliest Pleistocene dentaries and postcrania of Callorhinus gilmorei, and a partial dentary of early Pleistocene age identified as Callorhinus sp. The aforementioned material is ascribed to C. gilmorei due to the incipient single-rooted condition of the p1–2, retention of double-rooted p3–m1, and overall small size. The dentary identified as Callorhinus sp. exhibits a more derived pattern of tooth morphology, including single-rooted p1–p4 (and double-rooted m1), larger size than C. gilmorei, and in the size range of extant Callorhinus ursinus (which typically exhibit fused roots on all postcanine teeth). Fusion of postcanine roots began with the p2 and continued posteriorly, and is likely an adaptation to accommodate crowded teeth anteriorly in the jaws. Callorhinus gilmorei has previously been reported from the upper Pliocene of southern California and Japan, and this new record extends the range of this taxon further north in the Northeast Pacific. Callorhinus sp. is the most complete pinniped fossil to be described from the early Pleistocene of the Northeast Pacific. The wide biogeographic range of Callorhinus during the Pliocene and Pleistocene documents the persistence of this taxon, potentially as a Pliocene-Holocene anagenetic lineage. This highlights the antiquity of the Callorhinus lineage, which has persisted in the Northeast Pacific since the Pliocene, establishing it as the oldest and earliest diverging crown otariid.

Bayesian analysis of sea-level sensitivity to CO2 forcing across the mid-Pleistocene transition: possible implications for early-Pleistocene ice-sheet extent

2021 ◽  
Author(s):  
Parker Liautaud ◽  
Peter Huybers
Keyword(s):  
Energy Balance ◽  
Bayesian Analysis ◽  
Sea Level ◽  
Late Pleistocene ◽  
Radiative Forcing ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Model Parameters

<p><span>Foregoing studies have found that sea-level transitioned to becoming approximately twice as sensitive to CO</span><span><sub>2</sub></span><span> radiative forcing between the early and late Pleistocene (Chalk et al., 2017; Dyez et al., 2018). In this study we analyze the relationships among sea-level, orbital variations, and CO</span><span><sub>2</sub></span><span> observations in a time-dependent, zonally-averaged energy balance model having a simple ice sheet. Probability distributions for model parameters are inferred using a hierarchical Bayesian method representing model and data uncertainties, including those arising from uncertain geological age models. We find that well-established nonlinearities in the climate system can explain sea-level becoming 2.5x (2.1x - 4.5x) more sensitive to radiative forcing between 2 and 0 Ma. Denial-of-mechanism experiments show that the increase in sensitivity is diminished by 36% (31% - 39%) if omitting geometric effects associated with thickening of a larger ice sheet, by 81% (73% - 92%) if omitting the ice-albedo feedback, and by more than 96% (93% - 98%) if omitting both. We also show that prescribing a fixed sea-level age model leads to different inferences of ice-sheet dimension, planetary albedo, and lags in the response to radiative forcing than if using a more complete approach in which sea-level ages are jointly inferred with model physics. Consistency of the model ice-sheet with geologic constraints on the southern terminus of the Laurentide ice sheet can be obtained by prescribing lower basal shear stress during the early Pleistocene, but such more-expansive ice sheets imply lower CO</span><span><sub>2</sub></span><span> levels than would an ice-sheet having the same aspect ratio as in the late Pleistocene, exacerbating disagreements with </span><span>𝛿</span><span><sup>11</sup></span><span>B-derived CO</span><span><sub>2</sub></span><span> estimates. These results raise a number of possibilities, including that (1) geologic evidence for expansive early-Pleistocene ice sheets represents only intermittent and spatially-limited ice-margin advances, (2) </span><span>𝛿</span><span><sup>11</sup></span><span>B-derived CO</span><span><sub>2</sub></span><span> reconstructions are biased high, or (3) that another component of the global energy balance system, such as the average ice albedo or a process not included in our model, also changed through the middle Pleistocene. Future work will seek to better constrain early-Pleistocene CO</span><span><sub>2</sub></span><span> levels by way of a more complete incorporation of proxy uncertainties and biases into the Bayesian analysis.</span></p>

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