Work­ers un­earth a trove of fos­sils

A River­side County site yields camels, lla­mas, saber-toothed cats and horses, among other sur­prises.

Los Angeles Times - - Front Page - Thomas H. Maugh II and Amina Khan

It hap­pened more than a mil­lion years ago, but the fos­silized ev­i­dence pre­served the scene. A horse not much dif­fer­ent from mod­ern horses was en­joy­ing a cool drink at a wa­ter­ing hole in what is now San Ti­mo­teo Canyon when a saber-toothed cat sneaked up and grabbed it by the haunch.

Af­ter fin­ish­ing its meal, the cat left the skele­ton to be buried in mud from flash floods. That cat, or one very like it, even­tu­ally also ended up dead and its skele­ton joined the horse’s in the ac­cu­mu­lat­ing sed­i­ment.

And then, 1.4 mil­lion years later, South­ern Cal­i­for­nia Edi­son crews con­struct­ing a new sub­sta­tion for the grow­ing pop­u­la­tion of River­side County un­earthed the horse — tooth marks still dis­tinct on its leg — the cat and a “trea­sure trove” of fos­sils.

Ex­ca­va­tion at the site has so far re­vealed what may be Cal­i­for­nia’s old­est ex­am­ple of the saber-toothed cat

Smilodon gra­cilis, a spec­i­men more than a mil­lion years older than the Smilodon fa­talis from the La Brea tar pits, which carry an ar­ray of fos­sils dat­ing to as re­cently as 9,000 years ago.

Sci­en­tists so far have iden­ti­fied more than 1,450 spec­i­mens, in­clud­ing about 250 large ver­te­brate fos­sils and more than 1,220 fos­sils that are rab­bit-size or smaller.

“And we’re still count­ing,” said pa­le­on­tol­o­gist Robert Reynolds of LSA As­so­ci­ates of River­side, the

con­sult­ing pa­le­on­tol­o­gists who are han­dling the dig for South­ern Cal­i­for­nia Edi­son.

Other spec­i­mens in­clude lla­mas, horses and deer and more saber-toothed cats, some rare and oth­ers pre­vi­ously un­known. There is one of the ear­li­est ex­am­ples of a gi­ant ground sloth. Many of the fos­sils are in a re­mark­ably well-pre­served state, Reynolds said.

Smaller an­i­mals in­clude meadow mice, go­phers and kan­ga­roo rats. Some of the re­mains are found in fos­silized exc­reta, in­di­cat­ing that owls or hawks were hunt­ing in nearby ar­eas, then fly­ing in and de­posit­ing the re­mains of their din­ner on the site.

Re­searchers have also found re­mains of birch, pine, sy­camore, oak, wil­lows and cot­ton­woods, as well as cat­tails and horse­tails.

“I’ve been work­ing in this area for more than 40 years and have never seen con­cen­tra­tions of fos­sils like this,” Reynolds said. So far, he said, the team has found more than 30 dif­fer­ent species.

The fos­sils sharply in­crease the num­ber of spec­i­mens avail­able from what is known as the Irv­ing­to­nian North Amer­i­can Land Mam­mal Age, which stretches from about 1.9 mil­lion years ago to 250,000 years ago.

The find is also of great in­ter­est to ge­ol­o­gists who have been at­tempt­ing to de­duce the his­tory of the San Jac­into fault, a ma­jor fault that par­al­lels the bet­ter­known San An­dreas. Be­cause the fos­sils were lo­cated in once-flat land that has been formed into a hill by a suc­ces­sion of earth­quakes along the San Jac­into fault, the age of the fos­sils found there pro­vides a mea­sure of when ac­tiv­ity on that fault be­gan, said ge­ol­o­gist Jonathan C. Matti of the U.S. Ge­o­log­i­cal Sur­vey.

Com­par­i­son of the fos­sils with those from other sites re­vealed their age. That al­lowed sci­en­tists to de­duce that the earth­quakes caused by the San Jac­into fault that raised the land into hills had to be more re­cent than 1.4 mil­lion years ago.

“Any­time you get in­di­ca­tors … of how old rocks are, a ge­ol­o­gist is filled with joy,” Matti said. The new find sug­gests that the av­er­age slip rate along the fault is sub­stan­tially greater than ge­ol­o­gists had pre­vi­ously be­lieved. That, in turn, sug­gests a po­ten­tial for larger earth­quakes linked to it.

“I’m re­ally glad” that state law re­quires com­pa­nies to per­form such stud­ies at con­struc­tion sites, Matti added.

South­ern Cal­i­for­nia Edi­son has a team of 70 bi­ol­o­gists, pa­le­on­tol­o­gists and other sci­en­tists who monitor con­struc­tion sites specif­i­cally for ar­ti­facts. The team sus­pected that fos­sils might be present be­cause pa­le­on­tol­o­gist L. Barry Al­bright III, for­merly a grad­u­ate stu­dent at UC River­side and now on the fac­ulty of the Uni­ver­sity of North Florida, had dis­cov­ered fos­sils of the same age in sim­i­lar rock for­ma­tion else­where in the San Ti­mo­teo bad­lands. He found only a few species, how­ever.

Doug Mor­ton, a UC River­side ge­ol­o­gist who has mapped the area, said the find sur­prised him. “If some­body had asked me ahead of time what they would en­counter, I would have said ‘damn lit­tle,’ ” he said.

Reynolds said few peo­ple know about the find and the team will prob­a­bly not be­gin pub­lish­ing its re­sults un­til next April.

“This sounds like a very nice, di­verse as­sem­blage that has the po­ten­tial to pro­vide some very in­ter­est­ing in­for­ma­tion,” said Dr. John Har­ris, chief cu­ra­tor of the Page Mu­seum at the La Brea tar pits, who hasn’t seen the fos­sils. “They will be an im­por­tant ad­di­tion” to ex­ist­ing col­lec­tions.

On Mon­day af­ter­noon, re­searchers at LSA were gath­ered around a long ta­ble clean­ing up some of the finds. Pa­le­on­tol­o­gist Carl Ben­nett, a tat­tooed, mus­ta­chioed pa­le­on­tol­o­gist, was hunched over a sloth skull as long as his fore­arm, us­ing a whin­ing nee­dle-like tool to clear away a layer of dirt. The skull is “the best ground sloth west of Texas of this age,” Reynolds said.

Nearby, Reynolds was wash­ing down sand­stone par­ti­cles re­moved from around larger bones to look for ro­dents’ teeth, in­sects and other tiny ar­ti­facts that can pro­vide valu­able in­sight into cli­mate at the site. He pointed to pink­ish, fin­ger­tip-size fos­sils of sloth skin armor among the de­tri­tus.

Michael Stokes, a prepara­tor, ges­tured at the stoneen­cased re­mains of a horse that he said “looked like some­body had walked right through it.” Many peo­ple be­lieve skele­tons like those of di­nosaurs are laid out the way they died, he said, “but that’s not the way we find them in real life.”

Once the sci­en­tists have fin­ished with them, the fos­sils will be trans­ferred to the Western Sci­ence Cen­ter in Hemet for pub­lic dis­play. That will prob­a­bly hap­pen late next year.

Ex­ca­va­tion is com­plete at the site and the sub­sta­tion will open by the mid­dle of next year. Pa­le­on­tol­o­gists sus­pect there may be more fos­sils in undis­turbed ar­eas ad­ja­cent to the site, but so far, no one is look­ing.

RARE FIND:

Gina Fer­azzi

Michael Stokes re­con­structs the jaw of a saber-toothed cat. Sci­en­tists so far have iden­ti­fied more than 1,450 spec­i­mens ex­ca­vated at a con­struc­tion site, many well over 1mil­lion years old.

SIGNS OF A FIGHT:

Gina Fer­azzi

Rick Green­wood, di­rec­tor of cor­po­rate en­vi­ron­ment, health and safety at South­ern Cal­i­for­nia Edi­son, holds a pre­his­toric horse leg that has teeth marks from a saber-toothed cat that at­tacked it.

HOW IT HAP­PENED:

Leo James Si­mone

An artist’s ren­der­ing of an at­tack at a wa­ter­ing hole 1.4 mil­lion years ago.

HORSE FOS­SIL:

The con­cen­tra­tion of spec­i­mens found has amazed sci­en­tists work­ing on the site.

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