Rare fossils have been discovered alive

A dazzling game of color highlights a long-lost clam in Southern California. Credit: Jeff Goddard

Discovering a new species is always exciting, but also finding a living species that everyone assumed was lost over time. A small oyster, previously known only from fossils, was recently found living at Naples Point, up the coast from the University of California, Santa Barbara. The discovery appears in the magazine Zukes.

“It is not uncommon to find a living species known for the first time since fossil record“Especially in a well-studied area like Southern California,” said co-author Jeff Goddard, a research associate at the Marine Science Institute at the University of California, Santa Barbara. The water mollusk Neopilina galatheae – an entire class of animals believed to have disappeared 400 million years ago – but goes back to the time of all those wonderful animals captured by the La Brea Tar Pits. “

On low afternoon tide in November 2018, Goddard was flipping rocks for sea slugs at Naples Point, when a pair of tiny, translucent bivalves caught his eye. “Their shells were only 10 millimeters long,” he said. “But when they stretched out and started to wiggle around a white-striped foot longer than their shell, I realized I had never seen this species before.” This surprised Goddard, who spent decades in California’s tidal flats, including many years specifically at Naples Point. He immediately stopped what he was doing to take close-up pictures of interesting animals.

With high-quality photographs on hand, Goddard decided not to collect animals that seemed rare. After identifying their taxonomic family, he sent the images to Paul Valentich Scott, Honorary Curator of Pathology at the Santa Barbara Museum of Natural History. “I was surprised and fascinated,” Valentich Scott recalls. “I know this family of bivalves (Galeommatidae) very well along the coast of the Americas. It was something I had never seen before.”

He mentioned some possibilities to Goddard, but said he would need to see the animal in person for a proper evaluation. Therefore, Goddard returned to Naples Point to claim it quiet. But after two hours of combing only a few square meters, he has not yet discovered his prize. Species will continue to dodge him multiple times.

Rare fossils have been discovered alive

It takes a keen eye to watch the little clam (bottom center), perched next to this chiton on the tide pools at Naples Point. Credit: Jeff Goddard

After nine trips, in March 2019, and on the verge of giving up for good, Goddard turned another rock and saw the needle in the haystack: one specimen, next to a couple of tiny white nudibranchs and a large keton. Valentich Scott will finally get his sample, and the pair can finally work on identification.

Valentich Scott was even more astonished once he got his hands on the shell. He knew it belonged to a race belonging to one of the members in the Santa Barbara District, but this shell didn’t match any of them. This raised the exciting prospect that they had found a new species.

“This really started the hunt for me,” Valentich Scott said. “When I suspect that something is a new species, I need to trace all the scientific literature from 1758 to the present. It can be a daunting task, but with experience it can go very quickly.”

The researchers decided to check out an interesting reference to fossil species. They traced the illustrations of bivalves Bornia cooki from the paper describing the species in 1937. It appears to match the modern specimen. If confirmed, this means that Goddard did not find a new species, but some kind of living fossil.

It is worth noting that the scientist who described the species, George Willett, estimated that he had excavated and examined perhaps a million fossil specimens From the same location, Baldwin Hills in Los Angeles. However, he did not find B. cooki himself. Instead, he named it Edna Cook, a Baldwin Hills collector who found the only two known specimens.

Rare fossils have been discovered alive

The type model originally used by George Willett to describe species. Credit: Valentich Scott et al

Valentish Scott ordered Willett’s original specimen (now classified as Cymatioa cooki) from the Los Angeles County Museum of Natural History. This object, called a “species specimen,” serves to identify the species, so it is the ultimate arbiter of clam identification.

Meanwhile, Goddard found another specimen at Naples Point – a single empty shell in the sand under a boulder. After carefully comparing the specimens from Naples Point with the Willett fossil, Valentich-Scott concluded that they were of the same species. “It was very cool,” he recalls.

Despite its small size and hidden habitat, all this begs the question of how the clam has long eluded detection. “There is such a long history of snail collecting and pathology in Southern California — including people concerned about the difficulty of finding minute slugs — that it’s hard to believe that no one has even found the shells of our little gentleman,” Goddard said.

It is suspected that the clams may have arrived here in streams like plankton larvae, carried from the south during marine heat waves from 2014 through 2016. This enabled several marine species to extend their distribution northward, including several documented specifically in Naples Point. Depending on the animal’s growth rate and longevity, this could explain why no one had noticed C. cooki at the site before 2018, including Goddard, who has worked on slugs in Naples Point since 2002.

“The Pacific coast of Baja California has vast intertidal rock fields that stretch literally for miles, and I suspect that Cymatioa cooki probably lives in close association with the animals that burrow under those rocks,” Goddard said.

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

the quote: Discovering Rare Fossils Alive (2022, November 7) Retrieved on November 8, 2022 from https://phys.org/news/2022-11-rare-fossil-clam-alive.html

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