Meet the 'Mold Pig': OSU discovers invertebrate that lived 30 million years ago
CORVALLIS, Ore. – Fossils found preserved in amber have revealed a new family, genus and species of invertebrate that lived 30 million years, Oregon State University said.
The researcher responsible for the discovered informally calls the critter the "mold pig" - but it's scientific name is Sialomorpha dominicana, from the Greek words for fat hog (sialos) and shape (morphe).
"About 100 micrometers long, the mold pigs had flexible heads and four pairs of legs. They grew by molting their exoskeleton and fed mainly on fungi, supplementing that food source with small invertebrates," according to OSU.
The discovery is the work of George Poinar Jr. of the Oregon State University College of Science.
Poinar is "an international expert in using plant and animal life forms preserved in amber to learn more about the biology and ecology of the distant past," according to OSU.
“Every now and then we’ll find small, fragile, previously unknown fossil invertebrates in specialized habitats,” Poinar said. “And occasionally, as in the present case, a fragment of the original habitat from millions of years ago is preserved too. The mold pigs can’t be placed in any group of currently existing invertebrates – they share characteristics with both tardigrades, sometimes referred to as water bears or moss pigs, and mites but clearly belong to neither group.”
The amber yielded several hundred individual fossils.
“The large number of fossils provided additional evidence of their biology, including reproductive behavior, developmental stages and food,” Poinar said. “There is no extant group that these fossils fit into, and we have no knowledge of any of their descendants living today. This discovery shows that unique lineages were surviving in the mid-Tertiary.”
The Tertiary period began 65 million years ago, according to OSU, and lasted for more than 63 million years.
And despite the findings published in Invertebrate Biology along with Diane Nelson of East Tennessee State University, Poinar said the discovery creates new knowledge - and new questions.
“No claws are present at the end of their legs as they are with tardigrades and mites,” Poinar said. “Based on what we know about extant and extinct microinvertebrates, S. dominicana appears to represent a new phylum. The structure and developmental patterns of these fossils illustrate a time period when certain traits appeared among these types of animals. But we don’t know when the Sialomorpha lineage originated, how long it lasted, or whether there are descendants living today.”
