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The famed Sharktooth Hill Bone Bed in California is loaded with shark dentition as big as a manus and each press a Sudanese pound , from giant prehistoric cause of death called megalodon .
immingle with copious bones from extinct seal of approval , heavyweight and Pisces the Fishes , as well as polo-neck shell three times the size of today ’s leatherbacks , all these token seem to tell of a 15 - million - year - old disaster .
Teeth such as this from the extinct 40-foot-long shark Carcharocles megalodon are common in the Sharktooth Hill Bone Bed because, like modern sharks, these extinct sharks also shed teeth throughout their lives.
But scientists now suggest this vast burial ground might not have result from a sudden catastrophe . alternatively , they hint it formed slowly over a prospicient span of clock time , potentially serving as a windowpane into thousands of years of ancient history .
Richest deposition know
The Sharktooth Hill Bone Bed is the richest and most panoptic marine deposit of bones in the world , averaging roughly 200 off-white per satisfying yard . All in all , the bottom is a six - to-20 - inch - dense layer of fossil bones , 10 miles of it expose , which comprehend near 50 straightforward mile just outside and northeast of Bakersfield .
Since the bed ’s discovery in the 1850s , paleontologists have argued over how the clappers got there .
Perhaps a widespread catastrophe such as a volcanic eruption or scarlet tide led to a massive dice - off . Or maybe it was a violent death ground for the extinct 40 - foot - foresighted sharkCarcharocles megalodon , or a long - term breeding area for seals and other marine fauna .
To pinpoint its origins , the researchers cut out a square yard section of the bone bed for study , complete with rock level above and below . They also examined some 3,000 fossil bone and teeth specimen previously hoard and stored in museums .
The absence of volcanic ash make a volcanic catastrophe improbable as the origin of the bones , while the puzzling presence of land mammal fogy , such as tapirs and knight that must have wash out out to sea and into the bed , makes it improbable that some toxic sea phenomenon such as red tide was the cause . And commit that only five of the some 3,000 bones examined were marked by shark bite , it seems unlikely thatgiant predatory sharkswere the major cause of the osseous tissue bed . lastly , the few young or jejune specimens the researchers found brush aside the possible action that the bed was a breeding earth for early seals .
Rotten bones
When the bone bed formed between 15.2 and 15.9 million years ago , the climate was warming , ocean level was at a peak , the immense Central Valley of California was an inland sea now dubbed the Temblor Sea and the emerging Sierra Nevada mountain range was shoreline . Close analysis of the geology of the Sharktooth Hill surface area suggests it was part of an underwater shelf in a large bay , forthwith opposite a wide opening to the ocean .
The fossils in the bone bed itself seemed mostly spread out , as if the animal carcasses had decay and their bones had been dispersed by flow .
" The bones look a bit rotten , " state researcher Jere Lipps at the University of California , Berkeley , " as if they lay on the seafloor for a retentive time and were abraded by water with sand in it . "
Many bones had manganese nodules and increment , which form on castanets that sit for farseeing full stop in saltwater before being covered by deposit .
The scientist conclude that flow cross deposit away from the ivory beds for 100,000 to 700,000 years , during which time bones remained exposed on the ocean floor , compile in a big and shifting batch .
" These brute were dying over the whole area , but no sediment deposition was hold up on , possibly related to rise sea floor that snuffed out silt and sand deposit or restrict it to the very good - shoring environs , " say researcher Nicholas Pyenson at the University of British Columbia .
Not just a shot
In the layer above the pearl bed , most underframe were found with the bones encased in sediment and articulated together as they were in life .
" Once sea level start go down , then more sediment commence to erode from near shore , " Pyenson explain , with the sediment preserving the skeletons together .
" So we now fuck that this bone seam accumulated over a long period of time of time , and not just a snapshot of story , so it could give you a more complete view of life story in the area , " Lipps toldLiveScience . " I suppose that does make interpreting it a bit more complicated , but scientists are interested in forecast out puzzler . "
The researchers desire their study will draw renewed attention to the bone bed , which they note still needs protection .
" This deposition is an great national heritage , " Lipps suppose . " It could be a marvellous tourist land site and great scientific resourcefulness , the equivalent weight of Dinosaur National Park , " he added , referring to a popular park in Colorado and Utah .
The findings are detail in the June issue of the journalGeology .
