The latest Devonian nightmare: A prehistoric predator almost six feet long -- featuring beady eyes on a broad flat head and a perpetual smile covering a mouth bristling with 1.5-inch fangs.
Some 375 million years ago -- late in what scientists now call the Age of Fishes -- this leering, lobe-finned piscivore haunted river bottoms and other waterways of what would later became Arctic North America.
Its M.O. would have been as chilling as it was effective: Lay motionless in the murk until prey swam close and then pounce, ripping into scaled flesh with a powerful set of wide jaws.
After 10 years of field work in remote Ellesmere Island and detailed analysis back at the lab, scientists say they have discovered a new species of predatory fish based on fossils of at least 22 individuals.
Described in technical detail in the latest issue of Journal of Vertebrate Paleontology, the Laccognathus embryi lived during an era when vertebrates had yet to fully colonize land and its prehistoric cousins were just beginning to creep ashore. It appears to be the first North American species from a genus of extinct fishes previously found in Latvia and eastern Europe.
"I wouldn't want to be wading or swimming in waters where this animal lurked," said Edward "Ted" Daeschler, co-author of the paper and curator of vertebrate zoology at the Academy of Natural Sciences, in this story. "Clearly these Late Devonian ecosystems were vicious places, and Laccognathus filled the niche of a large, bottom-dwelling, sit-and-wait predator with a powerful bite."
Although the fossils were recovered from a siltstone deposit in southwestern Ellesmere Island, other deposits from about the same geological period persist in Alaska's Brooks Range and scattered locations of Interior mountains.
"Laccognathus embryi (or a closely related species) may very well have ranged widely across the northern parts of the Euramerican continent (which includes Alaska)," Daeschler said via email. "The area that is now Alaska certainly looked very different then, but any rocks deposited there by Late Devonian stream systems may very well have included Laccognathus.
"If I were to explore those rocks, I would have Laccognathus in mind as a possible fossil there," he added.
Daeschler was part of the same team that uncovered the Tiktaalik roseae -- another lobe-finned fish now celebrated as the "missing link" between fish and amphibians waddling ashore on four limbs. Daeschler and two of his current co-authors recovered the Tiktaalik fossils from the same Ellesmere site and reported their findings in this paper published in 2006 in Nature.
That find made such a startling international splash that New York Times writer John Noble Wilford characterized it as "as a powerful rebuttal to religious creationists, who hold a literal biblical view on the origins and development of life."
"Several well-preserved skeletons of the fossil fish were uncovered in sediments of former stream beds in the Canadian Arctic, 600 miles from the North Pole," that 2006 story added. "The skeletons have the fins and scales and other attributes of a giant fish, four to nine feet long.
"But on closer examination, scientists found telling anatomical traits of a transitional creature, a fish that is still a fish but exhibiting changes that anticipate the emergence of land animals -- a predecessor thus of amphibians, reptiles and dinosaurs, mammals and eventually humans."
During the Devonian Age, ranging from 416 to 360 million years ago, most of the Earth was covered by a warm colossal ocean flush with trilobites, filter feeders, bivalves, early sharks and fishes. Plant life had colonized the land with ferns and horsetails, and began producing the first forests and the earliest seed-bearing plants.
The Devonian "was a fish-eats-fish kind of world," Daeschler told National Geographic writer Christine Dell'Amore in this story about the research. "There was a real arms race going. If you [were a smaller fish and] didn't have good armor on your body, you were very vulnerable."
The oxygen-depleted shallows also saw the slinky arrival of lobe-finned fish like the Tiktaalik that would ultimately become the ancestors of all four-limbed tetrapods that came to dominate the terrestrial Earth.
Cousin to those transitional creatures would be the new Laccognathus embryi -- Laccognathus means "pitted jaw" and "embryi" honors Canadian geologist Ashton Embry, who identified the Devonian deposits in Ellesmore that led to the discoveries of the fossils.
"The body form and cranial features, including the presence of large … fangs, support an interpretation of Laccognathus as a large, benthic, sit-and-wait predator," the authors concluded in the paper.
Along with extending the range of the Laccognathus fishes to Arctic North America, the discovery also confirms that pieces of North America and Europe were in direct connection 370 million years ago, the authors said here.
"This study is the culmination of a lot of work in the field, in the fossil lab, and in the office," added lead author Jason Downs, in this story. "Our team collected the first fossils of Laccognathus almost 10 years ago, and the collection has grown with each subsequent field season. The quality and quantity of this collection will continue to shed new light on these unusual animals."
Contact Doug O'Harra at doug(at)alaskadispatch.com