JULY 2003
A New Temnospondyl Amphibian from Mazon Creek
There are still fossils from Mazon Creek that are being studied like this one
that was found by the Ramsdells from Pit 11 and is now at the Royal Ontario
Museum. An article describing it is in the current issue of Canadian Journal
of Earth Science by Stephen Godfrey. This concretion is an internal mold
with the original bone gone and infilled with kaolin. This was carefully removed
with a spray of sodium bicarbonate and latex casts were made for study. The mold
preserves the skull, parts of the body including the shoulder and hip areas and
parts of the digestive system. It is measured at 38.5 mm (about 1.5 in.) with
the skull being 40% of the length (10.5 mm by 10.5 mm wide or .5 in. by .5 in.).
This would indicate a juvenile. The eyes are relatively small and widely spaced
with sclerotic rings and a black disc in each eye thought to be stable degraded
retinal pigment (also found in other Mazon Creek fossils). The skull sutures
were not clear so a reconstruction was not possible. They found impressions of
about 20 teeth in the maxilla and premaxilla set that indicated there may have
been 28 teeth on the left side. The vomers have teeth also with at least 12
teeth on each vomer. There are rows of gill rakers (pharyngeal dental plates)
with about 54 plates per side. It has 12 to 13 short straight ribs. Not all the
shoulder girdle is present but there are fingers with sharply pointed unguals.
The size indicates large strong limbs. There is an endocast of a part of the
digestive tract and an oblong mass that may have been faecal material.
Unfortunately the specimen does not give enough information to identify it. They
place it within Temnospondyli.
Bakker is Back!!!
“Raptor Pack” a new novel by Bob Bakker is coming out this June and is available
at prepublication discounts at Barnes & Noble. It is illustrated by Michael
Skrepnick and is aimed at the younger reader. Also coming in June is an article
in Discovery Magazine about Bakker titled “Dinosaur Family Values”. Once again
he is stepping into tricky territory with stories of dinosaur behavior. He
believes that these savage predators were really nurturing protective family
oriented animals. Here is some of what is in the article. Bakker has been
working on a shed tooth theory and believes that the locations where many shed
teeth are found are communal feeding areas or lairs. Meaty parts of dinos were
carried there for all to feast on leaving many of their shed teeth along with
the bones. In 13 sites in Como Bluff teeth of adult and young allosaurs are
found. And these teeth are similar in structure meaning that both ages ate the
same food. But where are the teeth of teenagers? They are found near perennial
lakeshores where they must have migrated during the dry season. He also believes
that the whole camarasaur teeth rather than shed teeth found indicate that they
were migrating without stopping to eat. When high numbers of shed teeth are
found – these are feeding areas. He also states that finding clean complete dino
skeletons is near useless. The chewed up partial skeletons have more to tell. In
addition the article discusses the reaction of other paleontologists to Bakker’s
style of research. He seems to avoid peer reviewed journals to publish. But his
shed tooth theory is scheduled to be published by the University of Indiana
Press. Jack Horner argues that dinosaurs are always shedding teeth and that
doesn’t mean that it is a feeding area.
Cretaceous
Fish Tell Story of Migration
A Nature article by Carpenter et al. compares fossil fish to modern fish
to tell a story of migration. They studied the carbon, oxygen and strontium
isotopes of aragonite otoliths found in Late Cretaceous sediments from South
Dakota (Fox Hills Formation at 65-67 MYA). Otoliths are small calcitic spheres
from the inner ear of fish. These otoliths yield a record of the environments
the fish lived in at various stages of their lives. The fossil fish were
Vorhisia vulpes and the analysis of their otoliths indicate that they spawned in
brackish water (70-80% seawater), then moved to the open waters of the Western
Interior Seaway after one year, and returned to brackish water to spawn 3 years
later. They are similar to the otoliths of modern salmon. The analysis also
shows that the temperature of the seawater was 18 degrees C., which agrees with
the estimates of temperature from a leaf study and a study of other marine
molluscs from the location. It is fascinating what can be learned from
relatively little fossil material!
Exciting
Mice Evolution News from Chicago
Dr. Oliver Pergams, a postdoc at the University of Illinois at Chicago is
working on an exciting project at Brookfield Zoo and has just reported his work
in Nature. His study of the mitochondria DNA of local Chicago mice over
the last 100 years shows that evolution may indeed proceed amazingly fast. He
has studied DNA from the skins of mice in museums (dating from 1900-1949) in the
area and compared it to trapped (and released) mice around Chicago. He studied
the white-footed mouse (Peromyscus leucopus) rather than the common house mouse
(Mus musculus, an invader from Europe) and the prairie deer mouse, which was
squeezed out by the white-footed mouse. The genotype common in 1906 (called A)
when the first example of the newer genotype (called M) appeared is now rare and
the newer M form is now dominant.
Early
Chinese Writing on Tortoise Shells
Writing is believed to have originated in Iraq 5,200 YA and in China some 2,000
years later. But new findings now claim that there are signs of the origin of
Chinese writing on the shells of tortoises dated to 8,000 YA. However, most
western archaeologists question that the geometric marks can be linked to early
writing. The Chinese excavated a site called Jiahu radiocarbon dated by three
separate labs. They have found house foundations, pottery kilns, a variety of
animal bones and 349 graves, some with turquoise ornaments and bone flutes.
Tortoise shells were found in 24 graves with markings on 14 of them. In one case
the shell replaced the skull. Others have found markings on pottery dated to
6500 YA that may have been ownership marks that may have been precursors to
Chinese characters found about3200 YA at the end of the Shang dynasty. It is
interesting that many of the Shang dynasty characters were found on tortoise
shells also. It has been thought that these shells were often used for
divination. One of the main problems with finding the origin of writing is that
the early works were probably made on perishable materials. The controversy will
continue.
Karen Nordquist, ESCONI Paleontology Study Group
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