GEOLOGICAL SOCIETY OF THE PHILIPPINES

 

The Gastropod Genus Calyptraphorus (Strombidae: Mollusca): 
A Lazarus Taxon from the Pliocene of the Philippines

Tomoki Kase1 and Yolanda, M. Aguilar2

1Department of Geology and Paleontology, 
National Museum of Nature and Science, 4-1-1 Amakubo,
Tsukuba, Ibaraki, 305-0005, Japan 
(e-mail: kase@kahaku.go.jp)

2Petrolab, Mines and Geosciences Bureau,
North Avenue, Diliman, Quezon City, Philippines
(e-mail:yolagui@yahoo.com)

 

Abstract

Calyptraphorus is a characteristic stromboidean genus known to have appeared during the Campanian (Cretaceous) in northeast Brazil and Ghana, Africa , survived the K-Pg biotic crisis and became extinct before the end of Eocene. However, in a recent survey in the Philippines a late Early or early Late Pliocene congener was discovered from an outcrop of the Tartaro Formation exposed in Bayabas River in Angat municipality, province of Bulacan. The single specimen at hand is quite similar to, but slightly differs from the Eocene species recorded from southeastern United States and Pakistan. It is left unnamed because the sample is partly broken to be compared to other known species on the basis of its shell morphology. The significance of this finding  is that it extends the recorded stratigraphic range of the genus Calyptraphorus from the end of Eocene to late Early or early Late Pliocene leaving about 30 million years hiatus which classifies Calyptraphorus sp.  as a Lazarus taxon. The genus may have survived as a refugee taxon in the tropical Western Pacific, with low population density  and limited geographic distribution after the Eocene biotic crisis.


 
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