Saturday, 18 January 2014

Fossil Lanternfish from the Late Miocene of Los Angeles County, California.

Lanternfish (Myctophidae) are bioluminescent deepwater Fish found throughout the world's deep oceans, where they are thought to make up around 65% of the total biomass. The majority of Lanternfish are thought to migrate vertically at dawn and dusk; remaining below the photic zone during the day, but migrating upwards to feed at night. The Lanternfish have a fossil record going back to the Palaeocene in Eurasia and the Mediterranean Basin, but do not appear in the Americas until the Late Miocene of California.

In a paper published in the Journal of Vertebrate Paleontology in July 2013, John Denton of the Department of Ichthyology and Richard Gilder Graduate School at the American Museum of Natural History, describes three new Lanternfish fossils from the Late Miocene Modelo Formation near Sherman Oaks in the San Fernando Valley region of Los Angeles. All three are placed in modern genera, but none is assigned to a specific species. 

The first new fossil described is placed in the genus Bolinichthys. This is a 45 mm specimen preserved as part and counterpart in white diatomaceous shale. The cranium is largely intact, but preservation of the post-cranial skeleton is poor, and the jaws are partially obscured by another fossil, so the assignment of the specimen to genus level is considered provisional.

Bolinichthys sp. From the Late Miocene Modelo Formation of Los Angeles County, California. Denton (2013).

The second new specimen is placed in the genus Lampanyctus. This is a 72 mm specimen preserved as a single impression in white diatomaceous shale. The cranium and pectoral girdle are partially disarticulated, but most of the post-cranial skeleton is present.

Lampanyctus sp. From the Late Miocene Modelo Formation of Los Angeles County, California. Denton (2013).

The final new specimen is assigned to the genus Myctophum. This is a more-or-less complete post cranial skeleton preserved as a lateral impression in white diatomaceous shale.

Myctophum sp. From the Late Miocene Modelo Formation of Los Angeles County, California. Denton (2013).


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