A paleobiologist from University of California Santa Barbara has discovered a tiny "vampire" amoeba that existed millions of years ago.
Susannah Porter analyzed ancient fossils from the Chuar Group in the Grand Canyon, which used to be a seabed between 782 and 742 million years ago, and found holes measuring about one micrometer in diameter in seven of the species she examined.
The drill holes may have been produced by an ancient relative of Vampyrellidae amoebae, single-celled organisms that puncture holes on their prey so they can reach inside and suck the content of the cells.
Russian biologist Leon Semenowitj Cienkowski first discovered vampire amoebas in 1865, when he found red single-celled organisms that attacked algae by piercing through their cell walls and sucking their content.
Porter said that the holes could be the earliest evidence that eukaryotes were preyed upon. Eukaryotes are organisms, which include plants and animals, with complex cell or cells that contain nucleus and other organelles.
The holes, which the researcher found using electron microscope, were not also common in any individual species she examined and vary in sizes.
"These holes thus provide the oldest direct evidence for predation on eukaryotes," Porter wrote in her study, which was published in the Proceedings of the Royal Society B journal on May 18.
"Larger circular and half-moon-shaped holes in vase-shaped microfossils from the upper part of the unit may also be the work of 'tiny vampires', suggesting a diversity of eukaryovorous predators lived in the ancient Chuar sea."
Porter said that the evidence may offer hints on how life evolved on Earth and shed light on whether or not predation contributed to the diversification of the eukaryotes, which occurred about 800 million years ago.
Eukaryotes first appeared in the fossil record about 1.8 billion years ago, but rapid diversification only occurred around a billion years later.
Porter also said that she wants to know if oxygen has a role in predation levels through time, as the microfossils attacked by the vampiric organisms were likely phytoplankton that lived in oxygenated surface waters.
"That might tie the diversification of eukaryotes and the appearance of predators to evidence for increasing oxygen levels around 800 million years ago," Porter said.
