Evolution news: Cambrian creature may be ‘missing link’ to arthropods

The shrimp-like creature swam in the seas during the Cambian period as long as 500 million years ago. Believed to be an ancestor to invertebrates such as arthropods, the odd animal had five eyes mounted on stalks.

However, palaeontologists were shocked to discover those stalks supported compound eyes, positioned on a semi-circular fused head shield.

The Kylinxia fossils exhibit exquisite anatomical structures

Professor Fangchen Zhao

And this tiny sea critter – measuring some three inches (seven cm) – also boasted an impressively articulated upper body, 15 jointed and spine-tipped limbs, as well as surprisingly large, upward-curving ‘arms’ for attacking prey.

These features are already well-documented from numerous fossil records of other ancient arthropods.

But this bizarre animal is the first-ever to possess features from multiple animals.

Arthropods emerged as arguably the most successful animal groups on Earth during the Cambrian period (543 million to 490 million years ago).

This early success story means arthropods still compromise almost 80 percent of all species alive today.

And the discovery of this newly-discovered animal is hoped to help fill in some critical evolutionary gaps.

Six fossils said to be in excellent condition from southern China’s Yu’anshan Formation were analysed in the study.

The fossils revealed two eyes at the front of the stalk cluster were twice as large as the others.

In addition, soft tissues such as the alimentary canal, digestive glands, nerve tissue and ventral cord, and even expelled gut contents were well-preserved.

Professor Fangchen Zhao of the Chinese Academy of Sciences’ Institute of Palaeontology and Geology (NIPG), said: “The Kylinxia fossils exhibit exquisite anatomical structures.

“For example, nervous tissue, eyes and digestive system – these are soft body parts we usually cannot see in conventional fossils.”

The animal’s chimerical amalgamation of features from some of the earliest known arthropods is what stunned the scientists.

Its cluster of five eyestalks is also found in the ancestral arthropod Opabinia, while its dexterous appendages resembled those of the Anomalocaris Cambrian marine arthropod – dubbed the ‘world’s first apex predator’.

After examining and comparing all of its characteristics, the researchers concluded the early arthropod resolved evolutionary relationships between several ancestral lineages.

Its unexpectedly large forelimbs were probable precursors of structures that evolved in later arthropods.

This included mouthparts bringing to scorpions and spiders, and sensory antennae such as those found in modern-day insects and crustaceans.

Professor Han Zeng, a NIPG assistant, said: “Kylinxia represents a crucial transitional fossil predicted by Darwin’s evolutionary theory.

“It bridges the evolutionary gap from Anomalocaris to true arthropods and forms a key ‘missing lin

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