Cretaceous Ammonite Find Here First in Southeast Asia - CT

Philippine and Japanese scientists have described the 100 million-year old ammonite fossils found deep in the forests of Dugui Wala San Vicente in Virac as the first of its kind found in Southeast Asia.



Dr. Yasunari Shigeta of the National Museum for Nature and Science (NMNS) in Tokyo, Japan told the Tribune that among the nine Ammonite species they found at the Silungan ng Higante site, the Mortoniceras specie is the most important as it is the first found in Southeast Asia. Although the specie is widely distributed in North America, Japan and India, none had been found in the region before, the Japanese scientist said.

"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," Dr. Shigeta said, noting that their team would be the first to study it. He added that the ammonites found in Mansalay, Mindoro is about 160 million years old (Jurassic period) while those found in Comagaycay, San Andres is 110 million years old.

Dr. Shigeta was with his boss, NMNS curator-in-chief Dr. Tomoki Kase, when they joined the exploration team composed of Dr. Yolanda Aguilar, Wenceslao Mago, and Emolyn Azurin of the Mines and Geosciences Bureau (MGB) as well as geology division chief Roberto de Ocampo and museum curator Priscila Ong of the Philippine National Museum during the trip to the site from Mar. 15 to 18. The trip is in connection with their 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."

They were joined by Virac personnel officer Oseas Alberto, who found 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. It was the publication of an article in the Tribune that year that drew the attention of the National Museum, which sent a team to the site in April 2009.

Last week, 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 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.

Dr. Kase and Dr. Shigeta said 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, Dr. Aguilar said the Silungan site is far more biologically diverse as 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 names Sendon from MGB-5 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 team raised concerns in the Caramoran municipal government when they sought and got permission to go to the Obi coal exploration site. However, Dr. Aguilar said they only wanted to look at the rocks between the coal seams where fossils may be found. They never got there, though, as it was already too late to attempt the three-hour trek to the site.

Dr. Shigeta informed the Tribune that their 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.

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. Alberto 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 the rock outcrop.

Source: Catanduanes Tribune - 24 March 2010

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