2023-09-28 13:13:28
MADRID, 28 Sep. (EUROPA PRESS) –
The fang shella tubular-shelled mollusk found in all oceans, has long baffled scientists with its strange shape and uncertain evolutionary history.
But a new genomic study published in PNAS has finally unveiled the layers of these enigmatic creatures.
The tusk shells exhibit a mosaic of morphological and developmental characteristics that resemble those of other mollusk lineagessuch as tentacles resembling the arms of nautiluses (cephalopods), a unique form of shell development similar to that of clams (bivalves), and a partially degenerated head, which apparently represents an intermediate state between clams (bivalves). “headless”) and snails (with well-developed heads, gastropods).
These features have intrigued scientists for decades, as they suggest different ideas about the evolutionary history of tusk shells.
The researchers sequenced the complete genomes of two species of tusk shells and compared them to other mollusks such as clams, snails and nautiluses. Analysis reveals that the tusk shells They are most closely related to bivalves like clams than with cephalopods like nautiluses or gastropods like snails, which reverses previous assumptions.
“This really reshuffles our understanding of how these unusual mollusks fit into the evolutionary tree,” said Dr. Hao Song of the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS), first author of the study. cited by Diario del Pueblo online.
This discovery, along with careful analysis of the molecular clock, also prompts the reinterpretation of many important but controversial Cambrian fossils that show similarities to both tusk shells and clams. It also provides important information about how the unique body plans of shells and clams evolved.
“By reading their DNA, we can finally unravel how these strange ancient mollusks came to be,” said Dr. Hao Song. “More importantly, it helps us better understand the Cambrian explosion itself.”
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