evolution: a transitioning form out from the Cambrian (Introduction)

by David Turell , Wednesday, November 04, 2020, 23:03 (1478 days ago) @ David Turell

An arthropod with five eye stalks and visible soft parts:

https://cosmosmagazine.com/nature/evolution/five-eyes-and-quite-a-story-to-tell/?utm_so...

"The fossilised 520-million-year-old creature shown above had five eyes on stalks, but that’s only part of its attraction.

"Its body structure combines features from different groups of arthropods, researchers have discovered, providing new insights into the early evolutionary history of the most successful animals on Earth.

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"The previously undescribed species Kylinxia zhangi is named after a chimeric creature in Chinese mythology called Kylin and the Chinese word for shrimp. Six specimens were discovered in the Chengjiang Biota in Yunnan, which offers the most complete early animal fossils of the Cambrian era.

“'Owing to very special taphonomic conditions, the Kylinxia fossils exhibit exquisite anatomical structures,” says co-author Zhao Fangchen. “For example, nervous tissue, eyes and digestive system: these are soft body parts we usually cannot see in conventional fossils”

"Detailed anatomical examination shows that Kylinxia has distinctive features of true arthropods, including a hardened cuticle, a segmented trunk and jointed legs.

"However, it also has characteristics present in very ancestral forms, including the five eyes of Opabinia, known as the Cambrian “weird wonder”, and the raptorial appendages of Anomalocaris, the giant apex predator in the Cambrian ocean.

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“'Our results indicate that the evolutionary placement of Kylinxia is right between Anomalocaris and the true arthropods,” says co-author Zhu Maoyan. “Therefore, our finding reached the evolutionary root of the true arthropods.”

"As such, adds Zheng, it contributes “strong fossil evidence for the evolutionary theory of life'”.

Comment: This doesn't close the Ediacaran/Cambrian enormous morphological gap, but it begins to fill in the transitional gaps to more modern forms from Cambrian animals.