UNDER THE KANSAS SEA EXHIBIT'S 90-MILLION-YEAR-OLD FOSSILS COME FROM AN ANCIENT OCEAN FLOOR.

Byline: Phillip Zonkel Staff Writer

Blanketed by cool 68-degree water that was between 500 and 1,000 feet deep, the Kansas of years past was a stark contrast to today's prairie-land wheat belt.

That's right, Kansas.

Between 65 million and 90 million years ago, part of the Cretaceous Period, Kansas and much of the Great Plains states were part of what is known as the North American Inland Seaway, an immense waterway bordered by Alaska, Mexico, the Midwest and the Western states of Arizona, Utah and Idaho (an area 4,300 miles long and 750 miles wide). During this time span, giant reptiles, fish, squid and clams (not dinosaurs - they lived on land) inhabited the area.

This watery habitat hits dry land in ``Savage Ancient Seas,'' a new exhibit at the Natural History Museum of Los Angeles County. Through Oct. 9, more than 50 fossils and 26 different specimens of marine life from prehistoric Kansas, including giant turtles and lizards as well as microscopic organisms, are on display, many of them for the first time.

Some of the reconstructions are cast reproductions of original skeletons. In some circumstances, casts are the best, or only, means of showcasing a fossil. When only part of a skeleton is recovered, casting makes it possible to fill in the missing bones and complete a specimen. Also, fossilized remains are sometimes brittle and won't withstand the rigors of a traveling exhibition.

While some of these fossil finds will be new to geographic greenhorns, Dr. J.D. Stewart isn't wet behind the ears. An assistant curator in the museum's vertebrate paleontology department with an expertise in fossil fish and marine reptiles, the 49-year-old Hays, Kan., native started digging in the Great Plains dirt for fossils at age 10. In 1966, the high school sophomore discovered a new prehistoric marine reptile species.

Seven years later, during a hometown stroll, he made another unique discovery. Walking in a pasture half a mile off the highway, Stewart found a rodent skull sticking out of a hillside. An examination revealed the fossil to be a 30,000-year-old Ice Age gopher not thought to have inhabited the Kansas area. After excavating the site, Stewart and some fellow paleontologists unearthed the remains of a complete ecosystem with more than 1,000 fossils and 20 different specimens (lemmings, voles, ground squirrels, prairie dogs, mice, conifers and meadow grass).

``Part of (my interest in paleontology) is the buried treasure aspect. You don't know what you're going to dig up next. Almost anything is possible. There's so much that's unknown,'' says Stewart, who in 1985 earned a doctorate in systematics and ecology from the University of Kansas.

``There's also the scientific aspect or the same reason you like a murder mystery. You're trying to put the pieces together in your mind and in some cases, literally putting the pieces together in your lab.''

For Stewart, that puzzle-making fits perfectly. In fact, the exhibit is a homecoming of sorts.

``It's kind of nice to see old friends from Kansas out here in California,'' Stewart jokes.

However, he realizes everyone isn't a maniac for marine life. At least, not yet.

``If you go the professional meetings of paleontologists now, about 50 percent of the presentations are on dinosaurs. I don't know what's happened. It's like an epidemic. There's some irrational thing happening here. Not only the public, but some scientists have gone gaga over dinosaurs, like there's something better about them than anything else. I don't know why. They're all interesting.''

And so is the exhibit, he promises.

Pieces of the puzzle

Here are a few of the animals (and where their remains were found) that lived millions of years ago in the North American Inland Seaway and are now on display in the Savage Ancient Sea exhibit.

Archelon ischyros (``large turtle''), Pierre Shale of South Dakota. Found in the late '70s, this giant sea turtle, measuring 15 feet long and 17 feet wide, is the largest land or sea turtle ever discovered. It's 25 percent larger than the previous largest.

``Turtles got larger than we realized,'' Dr. J.D. Stewart, assistant curator, says. ``It's another example that almost any group of animals can retain larger size in water than they can on dry land.''

Elasmosaurus platyurus (``plate-boned lizard'' for the large plate bones of the shoulder and pelvis area), Niobrara Chalk formation of northwestern Kansas in 1860. This 42-foot-long marine reptile is distinguished by its long neck and tiny head. In 1869, Edward Drinker Cope, a paleontologist for a museum at the Philadelphia University of the Academy of Sciences, thought the creature's long neck was its tail and in his skeletal reconstruction placed the head on the wrong end. The following year, Othniel C. Marsh, a Yale college professor and paleontologist, publicly pointed out the error.

``Most reptiles don't have rocks in their stomach. But the Elasmosaurus do. There's some correlation between having these long necks and having rocks in their stomachs,'' Stewart says. ``Maybe they need to counterbalance that long neck. You don't want the tail wagging the dog.''

Platyceramus platinus (``flat dish''), Niobrara Chalk of northwestern Kansas in 1988. Fish fossils have been found inside many species of this giant clam. The fossils were actually schools of fish that lived inside the clam. It was a symbiotic relationship. Another one also existed on the outside with clusters of oysters and barnacles attached to the shell.

``Through time, there were actually four different communities of fish and clams that developed. It was a recurring relationship,'' Stewart says. ``It was like four different productions of Macbeth at different times with different actors.''

But the show must go on.

``The first part of the real detective story was the symbiosis. The other part was, 'What is the life orientation of the clams?' They're always found lying flat and people assumed they lived lying flat, but that didn't make sense,'' Stewart says. ``The reason the fish were stuck in there was because the clam fell over, for whatever reason, couldn't open up anymore and the fish and clam died together.''

Pteranodon sternbergi (``winged and toothless''), Niobrara Chalk formation of northwestern Kansas in 1988. This large flying reptile (its wingspan ranged from 6 to 26 feet and the skull could be 6 feet long) belonged to a group of animals that also included crocodiles and dinosaurs, but it is not a dinosaur.

The prevailing thought is that these animals were quadrupedal; however, some scientists think they were bipedal. That theory doesn't fly with Stewart.

``It's only recently that the bipedal hypothesis came about,'' he says. ``Not every new idea is a good idea.''

Tylosaurus proriger (``knob lizard'' for the bolbus snout area), Pierre Shale formation of northwestern Kansas. This 45-foot-long marine lizard is the largest Tylosaurus ever found. It could flex its lower jaw, allowing it to swallow large prey in one piece, much as a snake does.

``We actually have fossil skin for some of these critters. They have little diamond-shaped scales. Each scale has a lengthwise ridge along it,'' Stewart says. ``A blind man could probably identify various genera of mosasaurs (the family of marine lizards that Tylosaurus belongs to) because they didn't all have the same sort of scales.''

Xiphactinus audax (``sword spine''), Carlile Shale of northwestern Kansas in the late 1980s. These large predators with spikelike teeth swallowed their prey whole. For years, scientists suspected that Xiphactinus ate a smaller sharklike fish, Pachyrhizodus caninus, but had no evidence to prove it. In 1998, Stewart and a group of museum scientists went to western Kansas and dug up a partial Xiphactinus fossil.

``There's a shark's tooth on the ribs, which explains why the full skeleton wasn't there,'' Stewart says. ``When I got to looking in (the stomach) area, there's some jawbones that don't belong to this fish. They belong to (Pachyrhizodus). There's actually the head of one of these guys in its belly. Unknowingly, we collected the first evidence that Xiphactinus did eat Pachyrhizodus.''

- Phillip Zonkel

The facts

--What: ``Savage Ancient Seas,'' an exhibit of giant creatures who once lived in the ocean.

--Where: Natural History Museum of Los Angeles County, 900 Exposition Blvd., Los Angeles.

--When: 10 a.m. to 5 p.m. daily; through Oct. 9.

--How much: $8 adults, $5.50 seniors and students with ID, $2 children 5-12, children under 5 free.

--Information: [phone] or www.nhm.org.

CAPTION(S):

8 photos, box

Photo:

(1 -- 2 -- color) Display, above, features a 45-foot marine lizard, Tylosaurus, munching on a smaller mosasaur. Below, the flying reptile Pteranodon Sternbergi keeps watch over the visitors to the museum exhibit.

(3 -- 4 -- color) Xiphactinus Audax (sword ray), on exhibit at the Natural History Museum, is given a tooth brushing by assistant curator J.D. Stewart, above. At right is a school of skeletal remains of an 85-million-year-old, 6-foot-long Pachyrhizodus caninus fish.

(5 -- color) This is an example of Archelon, measuring 15 feet long, the largest sea turtle of any kind found.

(6 -- color) no caption (Savage Ancient Seas exhibit) (7) Students visiting the ``Savage Ancient Seas'' exhibit compare a chart of several species from the era.

Yael Swerdlow/Long Beach Press-Telegram

(8) This sharklike Pachyrhizodus caninus was swallowed whole by the larger Xiphactinus audax, a predator with spikelike teeth.