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'Very Strange Animal' Was First Marine Plant-Eater

Strange and crazy are just two words used when describing the first known plant-eating marine reptile.

'Very Strange Animal' Was First Marine Plant Eater

An animal described as part Dr. Seuss, part dinosaur has been identified as being the first known plant-eating marine reptile.

The reptile, which lived 242 million years ago in southern China, arose after the planet's largest mass extinction, revealing that dire times can result in animals with seemingly improbable features.

The crocodile-sized plant eater, named Atopodentatus unicus, aka "Uniquely Strangely Toothed," is described in the journal Science Advances.

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Senior author Nicholas Fraser of National Museums Scotland told Discovery News, "To me, it is very much in keeping with a Dr. Seuss creation!" said Senior author Nicholas Fraser of National Museums Scotland, adding that the Seuss tale, "The Things You Can Think" comes to mind.

Fraser and his team studied the fossils for the reptile, with a particular focus on what was previously thought to be a flamingo-like beak. The new analysis instead found that the "beak" was part of a hammerhead-shaped jaw apparatus that the reptile used to feed on plants on the ocean floor. Peg-like front teeth lined the jaw, which also had needle-shaped teeth. None of the teeth were suitable for eating meat.

Some sharks today have hammerheads, but their sharp teeth are definitely ready to sink into moving prey such as octopus and even other sharks.

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Co-author Olivier Rieppel of Chicago's The Field Museum said that the marine reptile's peg teeth were used "to scrape plants off rocks on the seafloor, and then it opened its mouth and sucked in the bits of plant material. Then it used its needle-like teeth as a sieve, trapping the plants and letting the water back out, like how whales filter-feed with their baleen."

The teeth are reminiscent of those of certain dinosaurs, such as plant-eating Nigersaurus. The body of A. unicus seemed to be dinosaur-like as well, given the creature's long neck and rather chunky mid section.

While the lineage of A. unicus is a mystery for now, the researchers speculate that it was an "aberrant sauropterygian." These were aquatic reptiles that developed from terrestrial ancestors at around the time of the Permian-Triassic extinction event 252 million years ago. Sauropterygians include plesiosaurs that, like A. unicus, breathed air, had flippers and often long necks.

'Very Strange Animal' Was First Marine Plant Eater: Page 2

An illustratino of the head of Atopodentatus. | Wang Yu, IVPP

As for A. unicus looking somewhat like an underwater dinosaur, Fraser said, "Maybe all these large extinct animals seem so far-removed from anything we know today that we automatically try to group them together."

He said that after the big extinction event, there was a major breakdown in the food chain. Over a period of 6–7 million years, a large range of different feeding strategies had become established among marine reptiles. Some of these animals became suction feeders, while others feasted only on mollusks or fish. Still other strategies emerged, including A. unicus taking advantage of seafloor plant life.

Michael Benton, a professor of vertebrate paleontology at the University of Bristol, told Discovery News that A. unicus "adds to the amazing explosion of marine reptiles during the massive recovery of life from the Permian-Triassic mass extinction."

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Xiao-Chun Wu of the Canadian Museum of Nature said, "The research is important not only for revealing the oldest record of herbivory with a bizarre head within marine reptiles, but also for us to understand the recovery mechanism of marine vertebrates, especially reptiles after the global extinction at the Permian-Triassic Transition."

Wu believes that further examination of the reptile's teeth using a highly magnified electronic microscope might reveal wear surfaces that could provide additional clues concerning what the animal was eating. He wonders if, instead of scraping off plants, A. unicus was "grabbing muddy piles with organisms, including algae and plant matter, which were shoveled together" in the mouth.

All agree, however, that the animal was a plant eater. A. unicus appears to have no living relatives, but there are modern marine reptiles that love plants. These include green sea turtles and the seaweed-eating marine iguana.

Shown is an artist's recreation of Atopodentatus (a.k.a. the "hammerhead").

Aug. 30, 2011 --

Evolution and natural selection have played a role in the ever-changing landscape of plants, animals, bacteria and fungi. Although species evolve as they find their niche and adapt to new opportunities, some animals have remained relatively unchanged over the course of history. These animals are known as living fossils. Compared to the animals on this list, humans are relative newcomers to this planet. Homo sapiens emerged out of Africa a mere 200,000 years ago. Many living fossils are considerably older than humans and other mammals; some have even outlasted the dinosaurs. In this slideshow, take an up-close look at animals that have persevered virtually unchanged through the ages and continue to thrive today. We begin with the platypus, an unusual egg-laying animal with fur, a bill and a venomous bite. Charles Darwin himself coined the term "living fossil" while observing the platypus. Native to eastern Australia, the animal is the only surviving example of its family, Ornithorhynchidae. This group of animals is believed to have split from mammals some 166 million years ago.

The horseshoe crab could hold the distinction of being the oldest animal species still in existence. Dating back to the Paleozoic era, the horseshoe crab existed on Earth before the dinosaurs and soldiered on through several mass extinction events. In 2008, a horseshoe crab fossil, the oldest in existence found so far, dated back to around 445 million years ago, according to a report by LiveScience.

The tadpole shrimp, Triops cancriformis, is another contender for the title of oldest living animal species. This shrimp is related to the horseshoe crab so its longevity should come as no surprise. According to a report by The Telegraph, the tadpole shrimp as it appears today is virtually identical to a fossil of a specimen that lived some 200 million years ago just as dinosaurs rose to prominence. Despite the animal's remarkable endurance, the tadpole shrimp is currently listed as an endangered species.

Once thought to be extinct in the same event that killed off the dinosaurs some 65 million years ago, the coelacanth is a lobe-finned fish that sparked a debate over whether this species represented a missing link between aquatic animals and four-legged terrestrial creatures, according to National Geographic. The animal was rediscovered in 1938 and only two species of coelacanth still exist today. In 2007, a fossilized coelacanth fin was found dating back roughly 400 million years.

Snapping turtles as we know them first walked the earth some 40 million years ago, but they have been virtually unchanged over the past 215 million years of their evolution, according to Tortoise Trust. Although not among the most endangered tortoises and turtles according to the Turtle Conservation Coalition, the snapping turtle is listed as threatened.

The more than 20 species of alligators and crocodiles living today have evolved beyond their more primitive ancestors. But the basic physical design of these reptiles has remained essentially the same for the past 320 million years or so. Alligators and crocodiles share a common ancestry, though the two groups separated from each other some 60 million years ago.

The nautilus is the most primitive cephalopod in existence, a group that includes the most complex squid and octopus. Dating back to more than half a billion years ago, the nautilus reached the high point in its evolution during the Paleozoic era about 505 million to 408 million years ago. Several species of nautilus still survive today -- relatively unchanged from their ancestral counterparts.

Goblin sharks are rare, deep-sea dwellers with a unique elongated nose that distinguishes them from other sharks. They're also ancient, and are between 112 million to 124 million years old as a species. Around 2,000 different species of fossil sharks have been discovered, according to the ReefQuest Centre for Shark Research. The earliest sharks predate the dinosaurs by more than 200 million years.

The cockroach is famous for being a survivor. These insects can survive for weeks without their heads and even withstand the fallout following a nuclear blast. Cockroaches are also an especially long-surviving animal. Roaches have thrived on Earth for some 320 million years, with an estimated 5 million to 10 million individual species ranging in shape, size and habitat. This photo shows Blaberus giganteus, one of the largest species of cockroach on Earth.

Hagfish may have had to endure a less-than-flattering name since scientists first described them in the 18th century. However, these famously ugly marine animals have existed for about half a billion years. The hagfish also represents an important evolutionary step in the development of vision. These ancient fish may have been among the earliest animals to evolve more complex, camera-like eyes as opposed to the strictly photosensitive vision possessed by more primitive species. As such, the hagfish represents a kind of missing link in the evolution of the eye.

Compared to other animals on this list, the mouse deer, better known as a chevrotain, is a relative newcomer. For a large mammal, however, it's relatively old. This animal is among the only survivors of a group of hoofed mammals that lived some 35 million years ago.