(a fossil Goodeid )
by Andreas Tveteraas, Norwegian
taken from the website : www.goodeiden.de
In 1971 the Mexican student
JULIO C. ARRIOLA discovered an extensive accumulation of fossil fish in the hill
country of "Barranca de Santa Rosa" close to the town Amatitan, which
is about 50 km north-east of Guadalajara, Mexico. The findings were handed over
to the ichthyologist JOSÉ ALVAREZ. Consequently, further investigations were
carried out. Also, the geological characteristics of the place of discovery were
The examination of the entire collected material indicated
that the fossils obviously belonged to the family of Goodeids, the Andropodium
was clearly visible. Details of the fin rays, sets of teeth, etc. showed in
comparison with modern Goodeids that it had to be an unknown genus.
The species was scientifically described by ALVAREZ and
ARRIOLA and given the name Tapatiaoccidentalis.
"Tapatia" is the Mexican name for women of the Guadalajara area. The
species' name "occidentalis" refers to the former distribution of the
fish in the east of Mexico. Tapatia occidentalis was a very small species. The
nomenclatural type had a length of 20.5 mm, the number of the dorsal- and
anal-fin-rays was 18.
Geological examinations revealed that the species had lived
about 9 million years ago in the Pliocene Epoch. The fossils were found in a
thin layer of sediment doubtlessly originating from a calm and shallow stretch
of water. The Barranca de Santa Rosa is close to the Rio Santiago and the
authors believe that in prehistoric times the river must have been on the same
level as the place of discovery. During the rainy season the river covered a
larger area. When the river moved back into its former bed at the end of the
rainy season, numerous fish were trapped in the remaining pools. When the living
conditions in these pools became worse, the fish died and were covered by a thin
layer of sediment, which preserved them after the pools dried out. The
petrifactions also contained some dark spots with parts of fish-bone. They
turned out to be the excrements of fish-eating animals, maybe birds. On the
basis of this discovery it is easy to imagine what happened millions of years
ago - fascinating.
Tapatia occidentalis was the first fossil Goodeid to be found. Others have been discovered in an area close to Mexico City. I do not know whether they have been identified yet, but I will try to find out and publish the results here.