First Superpredator Had Enormous Eyes on Stalks
(Credit: Katrina Kenny, University of Adelaide)
The world's first superpredator was a giant crustacean with enormous eyes and a razor sharp mouth, according to a new study in the journal Nature.
The over 3-foot-long marine predator sat at the top of Earth's first food chain, say scientists from the South Australian Museum and the University of Adelaide. They found fossils for the crustacean, named Anomalocaris, at Kangaroo Island, South Australia.
(Anomalocaris eye fossils, Credit: John Paterson, University of New England)
The exceptionally well-preserved fossil eyes for this Cambrian Period crusher reveal the predator had acute vision that would rival or even exceed that of most living insects and crustaceans.
The University of New England's John Paterson, who led the study, and his colleagues explain that Anomalocaris held the #1 spot in the earliest food chain due to its large body size, formidable grasping claws at the front of its head, and a circular mouth with razor-sharp serrations.
Three-feet-long might not seem like that much, but consider the size of other marine animals then. We're talking about some of the world's first animals, after about 100 million years or so of evolution. The oceans included, as they do today, unicellular microscopic organisms as well as creatures like the 1.5-foot-long Hurdia.
(Hurdia, Credit: Marianne Collins)
Supporting evidence of the predator's dominance includes damage to contemporaneous trilobites, and even its fossilised poo (or coprolites) containing the remains of its prey.
The eyesight of Anomalocaris, now understood thanks to the recent fossil discovery, proves that this marine dweller had superb vision to support its predator lifestyle near what is now Kangaroo Island. The site dates to 515 million years ago, so it's possible the bug-eyed hunter goes back even earlier in time.
The fossils represent compound eyes. These are the multi-faceted kind seen in arthropods, such as flies, crabs and kin. They are perhaps the largest of their kind to have ever existed, with each eye over 1 inch in length and containing over 16,000 lenses.
The number of lenses and other aspects of their optical design suggest that Anomalocaris would have seen its world with exceptional clarity while hunting in well-lit waters. Only a few arthropods, such as modern predatory dragonflies, have similar resolution.
(The eyes of dragonflies are among the most powerful compound eyes known, with tens of thousands of individual lenses. This species is Aeshna brevistyla. Credit: Alexis Tindall, South Australian Museum)
Such sophisticated, visual hunters within Cambrian communities would have accelerated the predator-prey 'arms race' that began during this important phase in early animal evolution over half a billion years ago.