Poor peepers are a problem, even if you are a big, bad sea scorpion.
One minute, you're an imperious predator, scouring the shallow waters for any prey in sight. The next, thanks to a post-extinction eye exam by Yale University scientists, you're reduced to trolling for weaker, soft-bodied animals you stumble upon at night.
Such is the lot of the giant pterygotid eurypterid, the largest arthropod that ever lived. A new paper by Yale paleontologists, published in the journal Biology Letters, dramatically re-interprets the creature's habits, capabilities, and ecological role. The paper is titled "What big eyes you have: The ecological role of giant pterygotid eurypterids."
"We thought it was this large, swimming predator that dominated Paleozoic seas," said Ross Anderson, a Yale graduate student and lead author of the paper. "But one thing it would need is to be able to find the prey, to see it."
Pterygotids, which could grow more than two meters long, roamed shallow, shoreline basins for 35 million years. Because of the creatures' size, the long-toothed grasping claws in front of their mouth, and their forward-facing, compound eyes, scientists have long believed these sea scorpions to be fearsome predators.
But research by Richard Laub of the Buffalo Museum of Science cast doubt on the ability of pterygotids' claws to penetrate armored prey. Yale's eye study further confirms the idea that pterygotids were not top predators.
"Our analysis shows that they could not see as well as other eurypterids and may have lived in dark or cloudy water. If their claws could not penetrate the armor of contemporary fish, the shells of cephalopods, or possibly even the cuticle of other eurypterids, they may have preyed on soft-bodied, slower-moving prey," said Derek Briggs, the G. Evelyn Hutchinson Professor of Geology & Geophysics at Yale and curator of invertebrate paleontology at the Yale Peabody Museum of Natural History. Briggs co-authored the paper.
Victoria McCoy, a Yale graduate student, developed an innovative mathematical analysis method to understand the properties of the sea scorpions' eyes. Yale also used imaging technology with backscattered electrons on a scanning electron microscope to reveal the eye lenses without damaging the fossils. The team compared the results with the eyes of other extinct species during the same period, as well as modern-day species such as the horseshoe crab.
Although the data couldn't be used to determine nearsightedness or farsightedness, it revealed a basic visual acuity level for the sea scorpions, which had thousands of eye lenses. "We measured the angle between the lenses of the eye itself," Anderson said. "The smaller the angle, the better the eyesight."
Unfortunately for pterygotids, their eyesight proved less than exceptional, note the researchers. In fact, their vision worsened as they grew larger. It certainly wasn't on par with high-level arthropod predators such as mantis shrimp and dragonflies, said the scientists.
"Maybe this thing was not a big predator, after all," Anderson said. "It's possible it was more of a scavenger that hunted at night. It forces us to think about these ecosystems in a very different way."
The Yale team's vision testing methodology may prove instrumental in understanding how other species functioned, as well. "You could use it on a number of different organisms," according to Anderson. "It will be particularly useful with other arthropod eyesight examinations."
Former Yale postdoctoral fellow Maria McNamara of University College Cork also co-authored the paper. The research began as a project in a fossil preservation class Briggs taught at Yale.
Jim Shelton | Eurek Alert!
Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH
Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Awards Funding
20.01.2017 | Materials Sciences
20.01.2017 | Life Sciences