نتایج جستجو برای: fossil record
تعداد نتایج: 121933 فیلتر نتایج به سال:
The poorly known fossil record of fur seals and sea lions (Otariidae) does not reflect their current diversity and widespread abundance. This limited fossil record contrasts with the more complete fossil records of other pinnipeds such as walruses (Odobenidae). The oldest known otariids appear 5-6 Ma after the earliest odobenids, and the remarkably derived craniodental morphology of otariids of...
Human longevity has been difficult to study using the fossil record due to constraints on paleodemography caused by a number of variables. These constraints include: small sample sizes; under-representation of age classes, particularly juveniles; and difficulties assessing adult age at death with high precision. Life span and other population statistics that are necessary for demography are dep...
The fossil record provides a wealth of data on the role of regional processes and historical events in shaping biological communities over a variety of time scales. The Quaternary record with its evidence of repeated climatic change shows that both terrestrial and marine species shifted independently rather than as cohesive assemblages over scales of thousands of years. Larger scale patterns al...
The co-occurrence of vertebrate trace and body fossils within a single geological formation is rare and the probability of these parallel records being contemporaneous (i.e. on or near the same bedding plane) is extremely low. We report here a late Pleistocene locality from the Victorian Volcanic Plains in south-eastern Australia in which demonstrably contemporaneous, but independently accumula...
The earliest evidence for animal life comes from the fossil record of 24-isopropylcholestane, a sterane found in Cryogenian deposits, and whose precursors are found in modern demosponges, but not choanoflagellates, calcareans, hexactinellids, or eumetazoans. However, many modern demosponges are also characterized by the presence of siliceous spicules, and there are no convincing demosponge spic...
Neandertals are the best-studied of all extinct hominins, with a rich fossil record sampling hundreds of individuals, roughly dating from between 350,000 and 40,000 years ago. Their distinct fossil remains have been retrieved from Portugal in the west to the Altai area in central Asia in the east and from below the waters of the North Sea in the north to a series of caves in Israel in the south...
The fossil record provides a wealth of data on the role of regional processes and historical events in shaping biological communities over a variety of time scales. The Quaternary record with its evidence of repeated climatic change shows that both terrestrial and marine species shifted independently rather than as cohesive assemblages over scales of thousands of years. Larger scale patterns al...
Simulation studies of the early origins of the modern phyla in the fossil record, and the rapid diversification that led to them, show that these are inevitable outcomes of rapid and long-lasting radiations. Recent advances in Cambrian stratigraphy have revealed a more precise picture of the early bilaterian radiation taking place during the earliest Terreneuvian Series, although several ambigu...
The recent study of monotreme paleobiology and phylogeny by Phillips et al. (1) emphasized that the crown group Monotremata may have diverged relatively recently. However, they failed to discuss several aspects of the monotreme fossil record and functional morphology that may have a significant bearing on their conclusions. It is important to note that the paucity of tachyglossid like monotreme...
A Carboniferous root apex reiterates the importance of the fossil record and classic developmental plant anatomy for modern evo-devo perspectives on plant diversity and evolution.
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