100-Million-Year-Old Fossils From Australia Reveal Three New Species of Monotreme

100-Million-Year-Old Fossils From Australia Reveal Three New Species of Monotreme
(Photo: Wikimedia Commons/Ypna)

Paleontologists found three new species of ancient monotreme, one of which was dubbed the "echidnapus." This species shared similar characteristics to the platypus and echidna.

3 New Species of Monotremes

In a new study, researchers found three fossils near Lightning Ridge, New South Wales. The remains were thought to be between 100 and 96 million years old.

Following the discovery, three new species of monotremes were identified. With the addition of this finding, Lightning Ridge now has six species of monotremes, making it the most varied monotreme location on Earth.

Three jaw bones were used to identify new species, two belonging to the previously known Steropodon galmani. One of the creatures quite resembles the modern platypus, and it may be the earliest known monotreme with a platypus-like body.

Parvopalus clytiei, which might have been a terrestrial creature like a brushtail phascogale
Dharragarra aurora, which shares similarities with modern platypus
Opalios splendens, otherwise dubbed the "echidnapus".

According to researchers who discovered the fossils, Lightning Ridge's diversity of species may indicate an evolutionary occurrence known as "monotreme radiation," in which numerous new species split out from a single ancestor to usher in an "age of monotremes" in Australia. However, not all paleontologists agree that the "age of monotremes" theory can be proven beyond a reasonable doubt.

The new study's lead author, Tim Flannery, an Australian Museum mammalogist, discovered fragments of five jaw bones in a drawer two years ago while perusing the institution's collection. The jaw bones were gathered over two decades prior by the miners at Lightning Ridge. Elizabeth Smith, the paper's co-author and a paleontologist at the Opal Centre in Australia, received the bones from her family and the museum afterward.

Kris Helgen, principal scientist of the Australian Museum and research author, stated that O. Spendens resembled an echidna in certain ways, with its small facial features. Still, its jawbone was more like that of a platypus.

According to DNA analysis, the divergence of platypus and echidna from other monotremes occurred approximately 18-55 million years ago.

However, Professor Helgen stated that it was difficult to determine if the echidna pus, assigned to its own family, Opalionidae, was the precise progenitor of current monotremes.

Evolutionary scientist Matt Phillips of the Queensland University of Technology, who was not involved in the study, stated that with the scant information at hand, the dental of O. Spendens connected it more to the Ornithorhynchids platypus family than to the oldest known monotreme, Teinolophos trustee.

However, Phillips thinks it would be fantastic to locate dental remnants for some confirmation. The paper is important because it significantly advances our understanding of Australia's Cretaceous mammal fauna, demonstrating that monotremes were formerly far more diversified and hinting at the dominance of monotremes among the larger-sized species of that fauna.

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What Are Monotremes?

Monotreme is any animal that belongs to the egg-laying Monotremata order, which comprises the terrestrial echidnas (family Tachyglossidae) and amphibious platypus (family Ornithorhynchidae) found in mainland Australia, Tasmania, the Australian island nation, and New Guinea. Mammals in the order Monotremata are the oldest extant.

Members of this order share primitive skeletal traits, including the shoulder girdle and cranial characteristics that have been lost in other living mammals, in addition to being egg layers (oviparous). Because of the perplexing mosaic, blending specialized traits and ancestral features has been challenging to ascertain relationships with other mammalian groupings.

Monotremes seem to share several skull characteristics with extinct early mammal species. Additional evidence, especially genetic data, relates Monotremata to more evolved mammals, specifically marsupials.