Rare fossil oyster discovered alive

Rare fossil oyster discovered alive
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Rare fossil oyster discovered alive

A dazzling play of color highlights Southern California’s long-lost clam. Credit: Jeff Goddard

Discovering a new species is always exciting, but so is finding a living species that everyone assumes disappeared with the passage of time. A small clam, previously known only from fossils, was recently found living at Naples Point, just above UC Santa Barbara. Discovery appears in the magazine animal keys.

“It’s not that common to find a known species alive for the first time. fossil recordThe aquatic mollusk Neopilina galatheae, which represents an entire class of animals thought to have disappeared 400 million years ago, but not La Brea Tar, said co-author Jeff Goddard, a research associate at the UC Santa Barbara Institute of Marine Sciences. It goes back to the time of all those wonderful animals caught by their pits.”

On an afternoon tide in November 2018, Goddard was knocking over rocks looking for naked sea snails when he spotted a pair of small, translucent bivalves at Naples Point. “Their shells were only 10 millimeters long,” he said. “But when they got longer and started waving a bright white-striped leg that was longer than their shell, I realized I had never seen this species before.” This particularly surprised Goddard, who spent decades in California’s tidal habitats, including many years at Naples Point. He immediately stopped his work to take close-up photos of the interesting animals.

With quality images in hand, Goddard decided not to collect rare animals. After identifying their taxonomic families, he sent the images to Paul Valentich-Scott, honorary curator of malacology at the Santa Barbara Museum of Natural History. “I was surprised and intrigued,” Valentich-Scott recalls. “I know this bivalve family (Galeommatidae) off the coast of America very well. It was something I had never seen before.”

He told Goddard about a few possibilities, but said he needed to see the animal in person to make an accurate assessment. So Goddard returned to Naples Point. clam. But after two hours of scanning only a few square meters, he still hadn’t seen his reward. The genre would continue to avoid him many more times.

Rare fossil oyster discovered alive

It takes a keen eye to spot the tiny mussel (bottom middle) sitting next to this chiton in the tide pools of Naples Point. Credit: Jeff Goddard

After nine trips, in March 2019 and almost ready to give up completely, Goddard turned another rock and spotted the needle in the haystack: a single specimen, next to a few small white nudibranchs and a large chiton. Valentich-Scott would eventually get his sample, and the couple could finally get to work on their identification.

Valentich-Scott was even more surprised when he picked up his shell. He knew it belonged to a single-membered genus in the Santa Barbara area, but this shell didn’t fit any of them. It raised the exciting possibility that they had found a new species.

“This really started the ‘hunt’ for me,” said Valentich-Scott. “When I suspect something is a new species, I have to go through all the scientific literature from 1758 to the present. It can be a daunting task, but with experience it can go pretty fast.”

Two researchers decided to check out an interesting reference. fossil species. they traced their drawings bivalves Bornia cookie from 1937 paper describing the type. It turned out to fit the modern example. If confirmed, that would mean that Goddard had found a living fossil, not a new species.

It is worth noting that George Willett, the scientist who described the species, estimated that he probably excavated and examined 1 million. fossil specimens from the same location, Baldwin Hills in Los Angeles. However, he himself never found B.cooki. He named it instead after Edna Cook, a Baldwin Hills collector who found two known specimens.

Rare fossil oyster discovered alive

Example of type used by George Willett to describe species. Credits: Valentich-Scott et al.

Valentich-Scott requested Willett’s original specimen (now classified as a Cymatioa cookie) from the Los Angeles County Museum of Natural History. This object, called a “type specimen”, serves to identify species, so it is the ultimate arbiter in oyster identification.

Meanwhile, Goddard found another specimen at Naples Point – a single empty shell in the sand under a rock. After carefully comparing the specimens at Naples Point with Willett’s fossil, Valentich-Scott concluded that they were the same species. “It was pretty remarkable,” he recalled.

Despite the small size and mysterious habitat, all this begs the question of how the oyster escaped detection for so long. “There’s such a long history of shell collecting and malacology in Southern California—including people interested in the more difficult-to-find micromollusks—that it’s hard to believe no one has even found the shells of our little sweetheart,” Goddard said.

He suspects the oysters may have arrived here on currents as planktonic larvae transported from the south during sea heat waves from 2014 to 2016. These enabled many marine species to extend their distribution northward, including those documented specifically at Naples Point. Based on the animal’s growth rate and longevity, this may explain why no one noticed C.cooki on the site before 2018, including Goddard, who has been working on nudibranchs at Naples Point since 2002.

“The Pacific coast of Baja California has vast intertidal rocky areas that literally stretch for miles,” Goddard said, “and I suspect there the Cymatioa cookie probably lived in close association with the animals that nested beneath these rocks.

More information:
Paul Valentich-Scott et al., with notes on the genus Cymatioa (Mollusca, Bivalvia, Galeommatoidea), a fossil species living off Southern California, ZooKeys (2022). DOI: 10.3897/zookeys.1128.95139

Quotation: Rare fossil oyster found alive (2022, 7 November) Retrieved 8 November 2022 from

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