نتایج جستجو برای: trace fossil

تعداد نتایج: 91986  

2007
Michael J. Oard

Embryos have been found in ‘old’ rocks on four continents, especially in Siberia, Nevada, Australia and China. They have been discovered in sedimentary rocks of even Late Neoproterozoic age, assuming the evolutionary geological column1 (figure 1). The Neoproterozoic is the period, so called, between 1 billion and 550 million years ago. This discovery was in the Doushantuo Formation, Guizhou Pro...

Journal: :American journal of physical anthropology 2013
Philip J Hopley Andy I R Herries Stephanie Edwards Baker Brian F Kuhn Colin G Menter

Following the discovery of the "Taung Child" (Australopithecus africanus) in 1924 in the Buxton-Norlim Limeworks near Taung, the fossil-bearing deposits associated with the Dart and Hrdlička pinnacles have been interpreted as the mined remnants of cave sediments that formed within the Plio-Pleistocene Thabaseek Tufa: either as a younger cave-fill or as contemporaneous carapace caves. When combi...

2009
Peter A. Rona Adolf Seilacher Colomban de Vargas Andrew J. Gooday Joan M. Bernhard Sam Bowser Costantino Vetriani Carl O. Wirsen Lauren Mullineaux Robert Sherrell J. Frederick Grassle Stephen Low Richard A. Lutz

We report new in situ observations and laboratory studies of specimens of a small (diameter 2.4–7.5 cm) strikingly hexagonal form originally described from sedimented steps in a wall of the axial valley of the Mid-Atlantic Ridge (water depth 3430–3575m) near 261N, 451W that appears to be identical to the iconic form Paleodictyon nodosum described as a trace fossil from Eocene flysch deposits at...

2017
Thomas A. Püschel Justin T. Gladman René Bobe William I. Sellers

Platyrrhines are a diverse group of primates that presently occupy a broad range of tropical-equatorial environments in the Americas. However, most of the fossil platyrrhine species of the early Miocene have been found at middle and high latitudes. Although the fossil record of New World monkeys has improved considerably over the past several years, it is still difficult to trace the origin of ...

Journal: :Development 1999
J W Valentine D Jablonski D H Erwin

The Cambrian explosion is named for the geologically sudden appearance of numerous metazoan body plans (many of living phyla) between about 530 and 520 million years ago, only 1.7% of the duration of the fossil record of animals. Earlier indications of metazoans are found in the Neoproterozic; minute trails suggesting bilaterian activity date from about 600 million years ago. Larger and more el...

2013
T. Denk G. W. Grimm

Shallowing of the Panama Sill and the closure of the Central American Seaway initiated the modern Loop Current–Gulf Stream circulation pattern during the Miocene, but no direct evidence has yet been provided for effective heat transport to the northern North Atlantic during that time. Climatic signals from 11 precisely dated plantbearing sedimentary rock formations in Iceland, spanning 15–0.8 m...

2013
Anna R. Holden John M. Harris Robert M. Timm

The La Brea Tar Pits, the world's richest and most important Late Pleistocene fossil locality, offers unsurpassed insights into southern California's past environments. Recent studies at Rancho La Brea document that insects serve as sensitive and valuable paleoecological and taphonomic indicators. Of the thousands of fossil bird and mammal bones recovered from the Tar Pits, insect trace damage ...

1998
Helene Horowitz Jay Hwang Samuel S. Lin

In particular, this paper deals with the lineage of birds, and how it may be possible to trace them back to their origin which appears to be from Dinosaurs (esp. Therapods). This paper is an application of tracing various lineages in the fossil record. The idea is that if we can find small changes with each successive form, then we can show their descent with modifications. Of most importance i...

2008
Conrad C. Labandeira

One of the most intensively examined and abundantly documented structures in the animal world is insect mouthparts. Major structural types of extant insect mouthparts are extensive, consisting of diverse variations in element structure within each of the five mouthpart regions•labrum, hypopharynx, mandibles, maxillae, and labium. Numerous instances of multielement fusion both within and among m...

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