The slot ancient ichthyosaur fossils came from high up in the Swiss Alps.

A fresh look at fossils uncovered decades ago is helping to supplement paleontologists' understanding of massive ocean-dwelling animals that thrived over 200 million years ago.

The fossil record for Late Triassic giant ichthyosaurs -- sometimes referred to as "fish lizards" -- is a bit thin, which has been a head-scratcher for scientists. University of Bonn paleontologist Martin Sander said it "remains a great mystery to this day." Sander is lead author of a study on rib fragments,

vertebrae and a huge tooth found high up in the Swiss Alps between 1976 and 1990. The paper published in the Journal of Vertebrate Paleontology this week makes sense of these nearly forgotten fossils.Ichthyosaurs likely resembled whales and dolphins, but were reptiles. Researchers estimate they could have weighed up to 80 tons.

The reexamined fossils came from three animals. A vertebra suggests one of them was about 66 feet (20 meters) in length. Sander called the tooth "particularly exciting" and "huge by ichthyosaur standards." The paper says the fossil confirms that at least some giant ichthyosaurs had teeth.