Fossil of oldest species of monstersauria lizard found in Hyogo

KOBE – A fossil unearthed in a 110-million-year-old stratum in Tanba, Hyogo Prefecture represents a new genus and species of the monstersauria lizard group, a museum has said. It is also the oldest monstersaury found so far.

The Hyogo Prefectural Museum of Nature and Human Activities in Sanda, Hyogo Prefecture, said on November 25 that the jawbone fossil is the first of the monstersauria group, which includes the family Helodermatidae, found in Japan. .

The fossil, dating to the early Cretaceous, was discovered in 2019. About 2 centimeters long, it was part of the left lower jaw of a lizard and has two teeth each measuring about 3 millimeters.

The double-edged sword-shaped teeth and long, slender jaw led paleontologists to determine that this was a new genus and a new species.

The lizard received the scientific name of “morohasaurus kamitakiensis”. The creature is estimated to be around 30 to 40 centimeters long.

According to the museum, only around ten monstersauria fossils have been reported in the world.

A study of the stratum showed that the jawbone fossil is about 10 million years older than the monstersauria found in North America, which had been called the oldest species.

The extant helodermatidae family consists of one genus and five species, all of which are found in North America and Central America.

“The discovery of this fossil raises the possibility that the monstersauria may have originated in eastern Eurasia,” said Tadahiro Ikeda, 43, a senior researcher at the museum who analyzed the fossil. “It is also an important resource for discovering the migrations and the origins of other creatures who lived during the same period.”

The fossil was discovered in the stratum called the Sasayama Group, which stretches across Tanba and Tanbasasayama in Hyogo Prefecture.

“Himeoolithus murakamii”, the world’s smallest dinosaur egg fossil (excluding those of dinosaur birds), was also found in the stratum.

The team’s discovery was published in an international academic journal.

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