88-1359 hockey team 1947-1948
Roxbury Latin School from 1948 Year Book
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This 1948 Year Book
turned up among materials in storage with Ben Maleson and Bob Godino when
John Barrett visited massachusetts november 1999 (R)
www.historyoftheuniverse.com/eukaryot.html-- From:
"Philip Brown"
| Block address To: "John Barrett"
Subject: Your comment has been published... Date: Fri,
21 Apr 2000 10:28:13 +0100 Add Addresses Your comment has been published on
the History of the Universe web site. Your comment has been given the title
Summary of earth history Your comment was: The age of the earth is estimated
fairly precisely by uranium half-life a little over 4.6 billion years. In
1950s Elso Barghoorn found bacterial fossils over three billion years old.
Molecular evidence suggests that archaeobacteria are quite different from
common ones - they include thermophiles occur in extreme envirnoments such
as hot deep sea vents and Yellowstone hot springs-- other archaebacetria
excrete methane or live in extreme salt environments. Lynn Margulis about
1970 did research to support an old hypothesis that a large host bacterium
engulfed smaller eubacteria, which survived in symbiosis leading to
mitchrondia and chloroplasts of eukaryotic organisms, which have complex
nuclei usually with more than one chromosome and a shield against
ultraviolet radiation. Among the earliest eukaryote fossils presently known
are red algae resembling the Bangiales order from Canada described by Nick
Butterfield and Andrew Knoll. In 1998 Harvard-Canadian earth scientist Paul
Hoffman and colleagues published evidence that between 730 and 580 million
years ago, ocean surfaces worldwide froze to the equator, but life survived
in oases such as near volcanoes, - carbon dioxide accumulated from volcanic
action,while photosynthesis was greatly reduced, and warm conditions
returned. About 544 million years ago at the Cambrian epoch calcium
skeletons appear suddenly in the fossil record, and familiar phyla including
arthropods, molluscs, and vertebrates can be recognized. The Burgess shale
in Yoho National Park British Columbia has exceptional preservation of soft
parts of these Cambrian animals because specimens were buried alive suddenly
by turbidity currents. For decades this was the only such site known, but
others have been discovered 1990s in China and Greenland. Since the Cambrian
there have been five major extinctions. The largest was at the end of the
Permian and Paleozoic around 250 million years ago, before the Traissic and
Mesozoic - heyday of reptiles and conifers. Other susbtantial extinctions
occurred in Ordovician, Upper Devonian [age of fish about 360 milllion years
ago] end Triassic [about 225 million years] when mammal-like reptiles lost
out to dinosaurs and end Cretacrous-Mesozoic 65 million years ago, when
ammonites and dinosaurs and many other groups suddenly became extinct,
probably because of a large comet hitting Chicxulub, Yucatan. an iridium
layer is important evidence here at the "K-T" boundary. It was sent by John
Barrett on 06 Apr 2000 This comment is published on the following page(s)
Eukaryotes( http://www.historyoftheuniverse.com/eukaryot.html )----2222-
From: "Philip Brown"
| Block address To: "John Barrett"
Subject: Your comment has been published... Date: Fri,
21 Apr 2000 10:27:28 +0100 Add Addresses Your comment has been published on
the History of the Universe web site. Your comment has been given the title
First photosynthetic organisms Your comment was: Cyanobacteria were probably
not the first photosynthetic organism, as there are very ancient green and
purple groups of bacteria, which, however, do not release substantial
amounts of oxygen the way cyanobacteria "blue-greens" do. The purple
photosynthetic bacterial group are believed by molecular evidence to include
the free-living ancestor of mitochondria of higher organisms. The term "blue
green algae" is NOT incorrect in a ECOLOGICAL context. Cladistically
blue-greens are prokaryotes, but they are included in nearly all major texts
on ALGAE, including Bold and Wynne's, and they are a central portion of the
ecology and paleobiology of ALGAE. It is not absolutely certain that all
early STROMATOLITES were formed by blue-greens, but they resemble those that
blue-greens form today in high salt environments such as coastal Australia,
where animal disturbance is lowered. Blue-greens were very widespread in the
Proterozoic, but they have been crowded from many habitats since the
Cambrian epoch around 540 million years ago. Blue-greens have contributed to
the oxygen of the atmosphere, though much comes from volcanoes. Between
three and 2.1 billion years ago, the oxygen continued to be removed from the
atmosphere by chemical reactions that formed major iron ore deposits. About
2.2 or 2.1 billion years ago the oxygen level of the atmosphere increased
greatly, and during the Paleozoic and Mesozoic epochs between about 540 and
250 million years ago, oxygen levels were probably much higher than today's
twenty per cent of air. This led to great fires in fern forests and may have
assisted evfolution of flight in insects, pterodactyls and birds. It was
sent by John Barrett on 13 Apr 2000 This comment is published on the
following page(s) Blue Green Bacteria( http://www.historyoftheuniverse.com/bluegree.html
)
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