95 ലക്ഷം വർഷങ്ങൾക്ക് മുൻപ് തിമിംഗലത്തിന്റെ അസ്ഥികൂടത്തിന് ചുറ്റും ഒത്തുകൂടിയ വിചിത്ര ജീവികൾ: പുതിയ കണ്ടെത്തൽ

Tiny skeletal plates recovered beside fossil whale bones in southern Denmark offer a rare glimpse of life around a whale carcass approximately 9.5 million years ago. Researchers have identified a new species of brittle star, Ophiura huebnerjenseni, from the Gram Clay Pit and suggest it represents the first fossil record of brittle stars associated with a whale fall.

The marine deposits in Gram Clay Pit are known for the discovery of several fossil whale skeletons and the largest megalodon vertebrae ever found. They also preserve a rich record of mollusks and other invertebrates, but until now, brittle stars had remained undetected. Two Museum of Southern Jutland staff members, Mette Elstrup and Trine Sørensen, teamed up with Ben Thuy at Musée national d'histoire naturelle in Luxembourg and Lea D. Numberger-Thuy at Dinosaurierpark Teufelsschlucht in Germany to search for the first brittle star remains from the Gram Formation.

The paper is published in the journal Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen.

A concentration of clues beside whale bones

The discovery of the brittle star specimens comes from sediment collected during the 2018 excavation of a beaked whale's lower jaw and associated vertebrae. The researchers washed and sieved the sediment, picked out microfossils under a microscope and examined selected specimens using scanning electron microscopy. Distinctive features of the brittle stars' skeletal plates revealed a previously undescribed species.

The crucial clue was where those plates occurred. "Only three samples taken directly beside the whale bones contained brittle-star remains. Samples from the same layer farther from the skeleton, and other comparison samples, yielded none," the lead author Thuy explains.

"We considered whether currents had simply concentrated the plates around the bones, or whether local chemical conditions had helped preserve them. However, sea-urchin fragments of comparable size and mineral composition occurred in every sample studied. This makes a preservation-only explanation less likely and supports the interpretation that the brittle stars lived on or close to the whale carcass," Thuy added.

An ancient counterpart to a modern seafloor gathering

When a dead whale reaches the seabed, its carcass provides a concentrated source of food, creating what scientists call a whale fall. Brittle stars are common around whale falls in today's oceans, but their association with these habitats has been missing from the fossil record. The discovery from Gram Clay Pit suggests this ecological connection was already present in the Late Miocene.

The fossils do not reveal exactly what the brittle stars ate, nor whether the species depended exclusively on whale falls. Drawing on comparisons with living communities, the researchers favor a more generalist animal that normally inhabited the surrounding seabed and gathered around the carcass in numbers large enough to leave a detectable fossil record.

"We interpret the site as a shallow-water whale fall at a stage when enrichment from the carcass supported opportunistic animals," said Elstrup. "We found no evidence for the later sulfide-based community stages that can develop at deep-sea whale falls. The discovery therefore adds a rare fossil perspective on how animals responded to a large food source on an ancient shallow-water seabed," Elstrup said.

A new species with a festival connection

The name Ophiura huebnerjenseni honors Holger Hübner and Thomas Jensen, founders of Wacken Open Air, in recognition of their commitment to the heavy metal music festival. They expressed their appreciation of the fossil honors, acknowledging that species names, once published, are a small piece of immortality.

In addition, the dark gray mud that has been an integral, downright legendary aspect of Wacken Open Air is probably sourced from the same geological deposits that yielded the new brittle-star fossils. "The clay that accumulated on the bottom of the ancient North Sea not only preserved the remains of a 9.5-million-year-old brittle star; it also turns Wacken Open Air into the muddy battlefield renowned by metalheads worldwide," concludes Numberger-Thuy.