That's no footprint, it's got no toes.A favorite spot among paleontologists and paleotourists, the rock formations near Isona, Spain, are famous for fossils of large bones and eggs. However, the sign that tells tourists about dinosaur footprints in one area may need updating. At the site in question, thousands of oval depressions currently identified as prints dot the sandstone landscape, says Jordi Martinell, a paleontologist at the University of Barcelona The University of Barcelona (Catalan: Universitat de Barcelona, UB) is a public university located in the city of Barcelona, Catalonia, Spain. It is a member of the Coimbra Group and Joan Lluís Vives Institute. . Ripples in the rocks and fossil crustacean crustacean (krŭstā`shən), primarily aquatic arthropod of the subphylum Crustacea. Most of the 44,000 crustacean species are marine, but there are many freshwater forms. burrows Burrows is a provincial electoral division in the Canadian province of Manitoba. It was created by redistribution in 1957, and formally came into existence in the provincial election of 1958. The riding is located in the northern part of Winnipeg. suggest that the site was a lagoon more than 65 million years ago. On average, the oval indentations are 43 centimeters long and 34 cm wide, and there's about one of them every square meter Noun 1. square meter - a centare is 1/100th of an are centare, square metre area unit, square measure - a system of units used to measure areas over a broad area. Scientists interpreted the pits as fossil footprints because of the area's abundance of dinosaur remains. Upon close inspection, none of the supposed tracks includes the hallmarks of a large animal's footprint, Martinell notes. There are no traces of toes. The pits have a U-shaped cross section, not the flat bottom expected from a big dinosaur foot. Also, sediments below the depression haven't been deformed de·formed adj. Distorted in form. , which would be expected if a heavy dinosaur had stepped in soft mud. Furthermore, the pits don't form clear trackways. Nor do many overlap--a situation unlikely if numerous dinosaurs had walked in the same area, says Martinell. If dinosaurs didn't make the oval depressions, then what did? In the August PALAIOS, he and his colleagues suggest that the fossils actually record the feeding behavior of stingrays. Evidence for the new interpretation comes from living stingrays. In portions of the Gulf of California Noun 1. Gulf of California - a gulf to the west of the mainland of Mexico Sea of Cortes Mexico, United Mexican States - a republic in southern North America; became independent from Spain in 1810 , for example, stingrays leave circular or oval pits 10 to 30 cm across in the mud as they forage forage Vegetable food, including corn and hay, of wild or domestic animals. Harvested, processed, and stored forage is called silage. Forage should be harvested in early maturity to avoid a decrease in protein and fibre content as crops mature. in the burrow-riddled tidal flats. Each square meter in these locations can hold up to three depressions, which closely resemble the indentations at Isona. Despite their abundance, the pits dug by living stingrays almost never overlap because the creatures usually don't look for food where the mud is already disturbed. |
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