Effects of Pleistocene environmental changes on the distribution and community structure of the mammalian fauna of Mexico

2010 ◽  
Vol 73 (3) ◽  
pp. 464-473 ◽  
Author(s):  
Gerardo Ceballos ◽  
Joaquín Arroyo-Cabrales ◽  
Eduardo Ponce

Biological communities in Mexico experienced profound changes in species composition and structure as a consequence of the environmental fluctuations during the Pleistocene. Based on the recent and fossil Mexican mammal checklists, we determine the distribution, composition, diversity, and community structure of late Pleistocene mammalian faunas, and analyze extinction patterns and response of individual species to environmental changes. We conclude that (1) differential extinctions occurred at family, genus, and species level, with a major impact on species heavier than 100 kg, including the extinction all proboscideans and several ruminants; (2) Pleistocene mammal communities in Mexico were more diverse than recent ones; and (3) the current assemblages of species are relatively young. Furthermore, Pleistocene relicts support the presence of biogeographic corridors; important refugia existed as well as centers of speciation in isolated regions. We identified seven corridors: eastern USA–Sierra Madre Oriental corridor, Rocky Mountains–Sierra Madre Occidental corridor, Central United States–Northern Mexico corridor, Transvolcanic Belt–Sierra Madre del Sur corridor, western USA–Baja California corridor, Tamaulipas–Central America gulf lowlands corridor, and Sonora–Central America Pacific lowlands corridor. Our study suggests that present mammalian assemblages are very different than the ones in the late Pleistocene.

2021 ◽  
pp. 1-17
Author(s):  
Laurie D. Grigg ◽  
Kevin J. Engle ◽  
Alison J. Smith ◽  
Bryan N. Shuman ◽  
Maximilian B. Mandl

Abstract A multiproxy record from Twin Ponds, VT, is used to reconstruct climatic variability during the late Pleistocene to early Holocene transition. Pollen, ostracodes, δ18O, and lithologic records from 13.5 to 9.0 cal ka BP are presented. Pollen- and ostracode-inferred climatic reconstructions are based on individual species’ environmental preferences and the modern analog technique. Principal components analysis of all proxies highlights the overall warming trend and centennial-scale climatic variability. During the Younger Dryas cooling event (YD), multiple proxies show evidence for cold winter conditions and increasing seasonality after 12.5 cal ka BP. The early Holocene shows an initial phase of rapid warming with a brief cold interval at 11.5 cal ka BP, followed by a more gradual warming; a cool, wet period from 11.2 to 10.8 cal ka BP; and cool, dry conditions from 10.8 to 10.2 cal ka BP. The record ends with steady warming and increasing moisture. Post-YD climatic variability has been observed at other sites in the northeastern United States and points to continued instability in the North Atlantic during the final phases of deglaciation.


2008 ◽  
Vol 70 (3) ◽  
pp. 426-432 ◽  
Author(s):  
R. Lee Lyman

AbstractFor more than fifty years it has been known that mammalian faunas of late-Pleistocene age are taxonomically unique and lack modern analogs. It has long been thought that nonanalog mammalian faunas are limited in North America to areas east of the Rocky Mountains and that late-Pleistocene mammalian faunas in the west were modern in taxonomic composition. A late-Pleistocene fauna from Marmes Rockshelter in southeastern Washington State has no modern analog and defines an area of maximum sympatry that indicates significantly cooler summers than are found in the area today. An earliest Holocene fauna from Marmes Rockshelter defines an area of maximum sympatry, including the site area, but contains a single tentatively identified taxon that may indicate slightly cooler than modern summers.


1991 ◽  
Vol 4 (3) ◽  
pp. 499 ◽  
Author(s):  
GI Jordan ◽  
RS Hill

Subtribe Banksiinae of the Proteaceae was diverse in Tasmania in the early and middle Tertiary, but is now restricted to two species, Banksia marginata and B. serrata. Rapid and extreme environmental changes during the Pleistocene are likely causes of the extinction of some Banksia species in Tasmania. Such extinctions may have been common in many taxonomic groups. The leaves and infructescences of Banksia kingii Jordan & Hill, sp. nov. are described from late Pleistocene sediments. This is the most recent macrofossil record of a now extinct species in Tasmania. Banksia kingii is related to the extant B. saxicola. Banksia strahanensis Jordan & Hill, sp. nov. (known only from a leaf and leaf fragments and related to B. spinulosa) is described from Early to Middle Pleistocene sediments in Tasmania. This represents the third Pleistocene macrofossil record of a plant species which is now extinct in Tasmania.


Author(s):  
Tony Hallam

We saw in Chapters 5 and 7 that the Quaternary was a time of low extinction rates despite a succession of strong environmental changes induced ultimately by climate. This began to change from a few tens of thousands of years ago with the arrival on our planet of Homo sapiens sapiens, which can be translated from the Latin as the rather smug ‘ultrawise Man’. It is widely accepted today that the Earth is undergoing a loss of species on a scale that would certainly rank in geological terms as a catastrophe, and has indeed, been dubbed ‘the sixth mass extinction’. Although the disturbance to the biosphere being created in modern times is more or less entirely attributable to human activity, we must use the best information available from historical, archaeological, and geological records to attempt to determine just when it began. Towards the end of the last ice age, known in Europe as the Würm and in North America as the Wisconsin, the continents were much richer in large mammals than today: for example, there were mammoths, mastodonts, and giant ground sloths in the Americas; woolly mammoths, elephants, rhinos, giant deer, bison, and hippos in northern Eurasia; and giant marsupials in Australia. Outside Africa most genera of large mammals, defined as exceeding 44 kilograms adult weight, disappeared within the past 100,000 years, an increasing number becoming extinct towards the end of that period. This indicates that there was a significant extinction event near the end of the Pleistocene. This event was not simultaneous across the world, however: it took place later in the Americas than Australia, and Africa and Asia have suffered fewer extinctions than other continents. There are three reasons for citing humans as the main reason for the late Pleistocene extinctions. First, the extinctions follow the appearance of humans in various parts of the world. Very few of the megafaunal extinctions that took place in the late Pleistocene can definitely be shown to pre-date the arrival of humans. There has, on the other hand, been a sequence of extinctions following human dispersal, culminating most recently on oceanic islands. Second, it was generally only large mammals that became extinct.


2017 ◽  
Vol 38 (2) ◽  
pp. 133-144 ◽  
Author(s):  
Martin Ivanov ◽  
Andrej Čerňanský

Completely preserved specimens of fossil snakes are extremely rare and ophidian palaeontologists are usually dependent only on disarticulated elements of a postcranial skeleton. Here we present an unusually well-preserved specimen of a small viperid snake from the Late Pleistocene firm travertine at the famous Gánovce-Hrádok Neanderthal mound in Slovakia. The complex study of both cranial and axial skeleton with well-preserved maxilla and basiparasphenoid confirms the presence of a viper from theVipera berusspecies group, and recent distribution ofV. berusspecies complex members supports identification of these preserved remains as belonging to the common adder,V. berus(Linnaeus, 1758). Associated faunal assemblages of the MFG-C and D mammalian fauna groups reported from the firm travertine indicate a humid climate in a predominantly woodland environment with typical forest species in the Gánovce-Hrádok vicinity throughout the Eemian optimum, and mixed forest and steppe environments in the late Eemian to early Weichselian stages. Occurrence ofV. berusdocuments the presence of open or semi-open biotopes with low vegetation. AlthoughV. berusoccurs in the Quaternary glacial/interglacial cycle and throughout the entire warm part, it never dominated herpetofaunal assemblages during the climatic optimum. Therefore, the presence ofV. berusmost likely indicates late Eemian or early Weichselian (interstadial) climatic conditions.


2003 ◽  
Vol 14 (3) ◽  
pp. 259-274 ◽  
Author(s):  
Hugh M. French ◽  
Mark Demitroff ◽  
Steve L. Forman

Paleobiology ◽  
1975 ◽  
Vol 1 (2) ◽  
pp. 195-204 ◽  
Author(s):  
Ronald G. Wolff

Analysis of several thousand mammalian fossils from late Pleistocene sediments in California provide data on sampling in mammalian paleoecology. Recovery of bones and teeth from the screenwashed bulk sediment sample residue is considered nearly total. Neither surface collecting alone, nor small bulk samples provide satisfactory quantitative data on original community structure or postmortem alterations in community organization. Minimum sample size for the analysis of diversity is discussed. Diversity and size-trophic ratios of the total identifiable mammalian component of this fauna (N = 1222) are similar to those expected in living communities, and therefore suggest adequate sampling, and minimally biased samples.


2008 ◽  
Vol 41 (2) ◽  
pp. 265-277 ◽  
Author(s):  
Anne de Vernal ◽  
Claude Hillaire-Marcel

ABSTRACT Palynological and isotopic analysis in a few deep-sea cores from the Labrador Sea reveals strong environmental changes related to the Late Pleistocene glacial fluctuations over eastern Canada. On the whole, the Labrador Sea was characterized by strong exchanges between North Atlantic water masses, Arctic outflows, and meltwater discharges from Laurentide, Greenland and lnuitian ice sheets. The penetration of temperate Atlantic waters persisted throughout most of the Late Pleistocene, with a brief interruption during the Late Wisconsinan. During this glacial substage, a slight but continuous meltwater runoff from the Laurentide ice margins grounded on the northern Labrador Shelf is indicated by relatively low 18O values and low-salinity (< 30‰) dinocyst assemblages. The calving of the ice margin, the melwater outflow and the subsequent dilution of surface waters offshore Labrador probably contributed to the dispersal of floating ice and, consequently, to a southward displacement of the polar front restraining the penetration of North Atlantic waters into the Labrador Sea. The advection of southern air masses along the Laurentide ice margins, shown by pollen assemblages, was favourable to abundant precipitation and therefore, high ice accumulation rates, especially over northern Labrador during the Late Wisconsinan. The déglaciation is marked by a brief, but significant, melting event of northern Laurentide ice shortly after 17 ka. The main glacial retreat occurred after ca. 11 ka. It allowed restoration of WSW-ENE atmospheric trajectories, increased phytoplanktonic productivity, and penetration of North Atlantic water masses into the Labrador Sea.


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