PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “FOSSILS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 829 records · Page 46Linked to original sources
PubMed2003

Fossil psychodoid flies and their relation to parasitic diseases.

Psychodid sand flies are blood-sucking fly vectors of several parasitic diseases. The oldest definitive record of this group is from the Lower Cretaceous amber of Lebanon (circa-135 to -125 My), but the high diversity within this group supports the idea that the psychodoids originated much earlier in history. The palaeontology demonstrates that the Lower Creataceous representatives of the different subfamilies of Psychodidae had similar morphology and were blood-feeders, which supports Hennig's hypothesis on the ground plan structure of this family. Historical relationship between sand flies and diseases is unclear up to the present time, but this relationship could be as old as the origin of psychodoids because of the blood-feeding life mode.

Animals↗
PubMed2006

Molecular trees of trypanosomes incongruent with fossil records of hosts.

Molecular trees of trypanosomes have confirmed conventionally accepted genera, but often produce topologies that are incongruent with knowledge of the evolution, systematics, and biogeography of hosts and vectors. These distorted topologies result largely from incorrect assumptions about molecular clocks. A host-based phylogenetic tree could serve as a broad outline against which the reasonability of molecular phylogenies could be evaluated. The host-based tree of trypanosomes presented here supports the " invertebrate first " hypothesis of trypanosome evolution, supports the monophyly of Trypanosomatidae, and indicates the digenetic lifestyle arose three times. An area cladogram of Leishmania supports origination in the Palaearctic during the Palaeocene.

Animals↗
PubMed1999

Evolution of the rearfoot. A model of adaptation with evidence from the fossil record.

The evolution of the human foot presents an obfuscation: explanations for its occurrence and the exact nature of mechanisms of change are still not fully understood. This article outlines a model of adaptation from a primitive ape foot and presents this as a hypothesis. Evidence substantiating the hypothesis is then presented, which explains many of the large-scale features distinctive to the human foot. Further evidence is then presented that goes some way toward explaining the sequence of modification with first the lateral side becoming adapted for terrestrial function followed by the medial side. Paradoxically, this was hypothesized by Morton more than half a century ago in his "hypothetical prehuman foot," though it was not accepted favorably at the time.

Adaptation, Biological↗
PubMed1998

[Evaluation of parasitic risks related to the revitalization of the Ferlo fossil valley (Senegal)].

In order to assess the parasitic risks related to Ferlo's valley water launching, a study has been carried out from september 15 to october 10, 1996 in 12 villages. Four villages surrounding the Guiers lake, four lower within lower Ferlo already water launched 7 years ago, and four villages within upper Ferlo not water launched. Malaria strikes at hypoendemic level in the villages surrounding the Guiers lake (p.i = 6.2%) and at mesoendemic level in the area stretching along lower (P.I = 37.6%) and upper Ferlo (P.I = 34.3%) The prevalence rate of urinary bilharziosis is 0.002% in the first area, 1.3% in the second one and 14.5% in the third area. In these areas, intestinal parasitosis were prevailing respectively at rates of 38.2%, 36.4% and 22.2%. Although, there is no reason to fear immediately a worsening of the epidemiological situation due to Ferlo's valley revitalisation project, nevertheless, appropriate steps should be taken right now aiming at tacking the extension of conditions related to hydric medium.

Adolescent↗