the shores of Lake Otero and in the surrounding grasslands. Columbian mammoths, ground sloths, ancient camels, dire wolves, lions, and saber-toothed cats—also known as saber-toothed tigers, though not closely related to tigers—all crossed the Tularosa Basin where the dunes lie presently. The animals left fossil footprints as they walked the muddy shores of Lake Otero, their body weight compressing the wet clay and gypsum. The fragile tracks are uncovered by the wind, then rapidly erode away, with many tracks disappearing after only two years. Scattered along the now dried lakebed are trackways of ancient camels and Columbian mammoths. The fossilized footprints appear to gather around ancient pools of water. For 80 years, only a small collection of fossil footprints had been found in the park; however, a group of scientists noticed dark spots dotting the expanse of the lakebed that appeared to be footprints. During the 2010s, footprints of a dire wolf were discovered beside ancient seeds dated to more than 18,000 years ago. The fossil footprints of ground sloths have also been found in the park. Paleolithic human footprints are sometimes found interacting with Ice Age animals. One set of footprints shows the stalking of sloths. The paleo-humans who lived in the Tularosa Basin left behind no other evidence of their passage. Though stone flakes from toolmaking, arrowheads, and spear points are found in surrounding areas, they are the artifacts of humans who lived after the Ice Age. The lakebed is nearly devoid of a single artifact from before the Spanish exploration in the 1500s. In a study of exposed outcrops of Lake Otero in 2021, Bennett et al. reveal numerous human footprints dating to about 23,000 to 21,000 years ago which provide strong evidence of pre-Clovis occupation of the American continents. Carnivores Dire wolves lived in North and South America during the Pleistocene. Standing at about 2.6–2.8 feet (80–85 cm) tall and weighing 130–150 pounds (60–68 kg), they were about the same size as modern gray wolves, but with a heavier, more muscular build. They had powerful jaws, with a stronger bite than modern wolves, and probably hunted in packs, allowing them to target larger prey such as horses and bison. During the Pleistocene, large cats lived throughout the world, including lions in North America. About four feet (1.2 m) tall at the shoulder and weighing over 500 pounds (230 kg), American lions had long, slender legs for