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100-million-year-old fossil found in Bicol

A joint team of Filipino and Japanese scientists has discovered on this island in Bicol ammonite fossils said to be 100 million years old, the Catanduanes Tribune said in its March 24 issue.

Ammonite Discovered at the Silungan ng Higante (Giant’s Haven) deep in the forest of Dugui Wala, barangay San Vicente in this capital town in Bicol region in the south of Luzon, Dr. Yasanuri Shigeta of the National Museum for Nature and Science (NMNS) in Tokyo, Japan, said last week that they found the fossils of nine ammonite species in the area, the first of its kind found in Southeast Asia.

Classified among prehistoric animals, the said ammonites first appeared about 240 million years ago, though they descended from straight-shelled cephalopods called bacrites that date back to the Devonian, about 415 million years ago.

Ammonites were predatory, squid-like creatures that lived inside coil-shaped shells. They were prolific breeders, lived in schools and are among the most abundant fossils found today. They went extinct with the dinosaurs 65 million years ago. Scientists use the various shapes and sizes of ammonite shells that appeared and disappeared through the ages to date other fossils.

The most important among the species found by the team, Shigeta said in the Tribune article, is the Mortoniceras, the first found in Southeast Asia.

Although the species is believed to be widely distributed in North America, Japan and India, Shigeta said, none had been found in those areas.

“Mortoniceras is an index ammonite, meaning its presence would indicate the age of the rock it is embedded in as about 100 million years old or in the Cretaceous period,” the Japanese scientist said in Catanduanes Tribune, noting that his team would be the first to study it.

He added that the ammonites recently found in Mansalay, Mindoro, are about 160 million years old (Jurassic period) while those found in Comagaycay, San Andres, Catanduanes, is 110 million years old.

Joining the team which undertook the exploration from March 15 to 18 was NMNS curator-in-chief Dr. Tomoki Kase. Also with them were Dr. Yolanda Aguilar, Wenceslao Mago and Emolyn Azurin of the Mines and Geosciences Bureau (MGB) of the Philippines’ Department of Environment and Natural Resources, MGB geology division chief Roberto de Ocampo and curator Priscila Ong of the Philippine National Museum.

The undertaking was in connection with a joint research project on “Collection Building and Natural History Studies in the Philippines: Tracing the Origin of High Marine Biodiversity in the Indo-Pacific through Fossil Studies.”

Virac personnel officer Oseas Alberto joined the team. Alberto first discovered the ammonite site by accident in 2007 while on a trek to get samples of small endemic fishes in mountain streams and rivers for possible breeding purposes.

The Catanduanes Tribune published the Alberto story on the find that year which caught the attention of the National Museum, and sent a team to the site in April 2009, the news report said.

The team also found part of a fossil of a belemnite, an extinct group of marine cephalopods very similar to the squid and closely related to the cuttlefish, the news report said.

The belemnites possessed an ink sac, but unlike the squid, they had 10 arms and no tentacles. The part that remained of the belemnite, which could be as long as three meters or 10 feet, is the back part of the shell and it looks like a slender bullet, the Tribune said.

The Japanese experts said in the news report that the Dugui ammonites could be found in a one-meter layer of sandstone at the bottom of the Silungan ng Higante rock outcrop, with the belemnite finds in the 20-centimeter thick muddy sandstone just below it.

While the Comagaycay site is older than the Dugui site, Aguilar said in Tribune that the Silungan site is far more biologically diverse because it has seashells, gastropods, sea urchins, squids, annelids or segmented worms and rudists, which are bivalves of a strange shape.

The team also went three kilometers up the Comagaycay River to look for ammonite samples but found only a small one embedded in a rocky bank.

The site was discovered by a geologist, a certain Sendon from the MGB regional office for Bicol based in Legazpi City in 1984 while the agency and Japanese expert Dr. Wataro Hashimoto found protozoan microscopic fossils belonging to the Cretaceous period at Bunag-bunag point in the same town, the news report said.

While the team did not find any fossil of a marine reptile, the possibility that there could be remnants of marine dinosaurs in the Silungan site remains, the Tribune said.

Alberto said he is still looking for a huge bone that was said to have been stored by an old man in one of the recesses of a labyrinthine cavern at the top of a rock outcrop.

The study’s objectives are to date the enclosing rock of the fossil and study the life habits of the strange marine animals that existed long before they became extinct, Dr. Shigeta told the Tribune.

Source: Business Mirror


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