Large predatory worms migrated on the seabed to 5.3 million years ago

An international study in which the University of Granada participated – recently published in the journal Scientific Reports–Has identified a new fossil record of these mysterious animals in northeastern Taiwan (China), in Miocene Age marine sediments (between 23 and 5.3 million years ago)

These organisms, like the Bobbit worm today (Eunice aphroditois), they were about 2 m long and 3 cm in diameter and lived in holes

An international study in which the University of Granada (UGR) participated (recently published in the prestigious journal Scientific Reports) has revealed that large predatory worms inhabited the seabed during the Miocene Age (23- 5.3 million years ago).

The scientists identified a new fossil record (indirect remnants of animal activity such as, for example, dinosaur tracks, fossil feces, insect nests, or holes) associated with these mysterious animals, which may have preceded the Bobbit mite today (Eunice aphroditois). Based on the reconstruction of large holes observed in Miocene-aged marine sediments from northeastern Taiwan (China), the researchers concluded that these fossils may have found seabed on the continent Eurasian about 20 million years ago.

Olmo Míguez Salas of the Department of Stratigraphy and Palaeontology (Research Group of Ichnology and Palaeoenvironment) UGR participated in the study, which was conducted as part of a project funded by the Taiwanese Ministry of Science and Technology (MOST, 2018) from which the person- beneficiary research.

Míguez Salas and the other researchers built this new fossil record, which they named Pennichnus formosae. It consists of an L-shaped hole, about 2 m long and 2-3 cm in diameter, showing the size and shape of the organism – Eunice aphroditois – that made the structure .

Bobbit worms hide in long, narrow holes in the seabed and move themselves up to catch prey with their strong jaws. The authors suggest that the movement involved in capturing their prey and returning to their hole caused a number of changes to the structure of the holes. These changes are preserved in the Pennichnus formosae and are indicative of the deformation of the sediment around the upper part of the hole. A detailed analysis revealed a high density of iron in this high region, which, the researchers believe, may reveal that the worms rebuild the opening into the hole by secreting a type of mucus to strengthen the wall, as bacteria that feed on this mucus forms. iron-rich environments.

Although marine invertebrates have existed since early Paleozoic, their bodies are mostly made up of soft tissue and are therefore rarely conserved. The fossil record found in this study is believed to be the earliest sample of an underground ambush predator.

Olmo Míguez Salas notes that this finding “provides a rare insight into the behavior of these creatures under the seabed and also highlights the value of studying fossil records to determine the behavior of organisms from the time. to understand the past. ”

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