from the world's big
Scientists uncovered the secrets of what drove some of the world's last remaining woolly mammoths to extinction.
Every summer, children on the Alaskan island of St Paul cool down in Lake Hill, a crater lake in an extinct volcano – unaware of the mysteries that lie beneath.
Batrachopus grandis, an ancient crocodylomorph, may have chased down land prey on its own two feet.
Walking the walk<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzM5MjIyOS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYwMDM5NDYxN30.vSptOKk7U7Vi6UGUrVSrlDZDA0KE27a4Hi506qS7_MQ/img.jpg?width=1245&coordinates=0%2C0%2C145%2C0&height=700" id="4984d" class="rm-shortcode" data-rm-shortcode-id="ca91bf364c9dcf5752919b5105bbcb2f" data-rm-shortcode-name="rebelmouse-image" alt="A photograph of Batrachopus grandis track impressions found at Jinju Formation." />
A photograph of Batrachopus grandis track impressions found at Jinju Formation.
An evolving understanding<div class="rm-shortcode" data-media_id="bM8XiiEp" data-player_id="FvQKszTI" data-rm-shortcode-id="217e12c49e7fd202232637b5487313ba"> <div id="botr_bM8XiiEp_FvQKszTI_div" class="jwplayer-media" data-jwplayer-video-src="https://content.jwplatform.com/players/bM8XiiEp-FvQKszTI.js"> <img src="https://cdn.jwplayer.com/thumbs/bM8XiiEp-1920.jpg" class="jwplayer-media-preview" /> </div> <script src="https://content.jwplatform.com/players/bM8XiiEp-FvQKszTI.js"></script> </div> <p>For now, the only evidence for <em>Batrachopus grandis</em> exists in the footprints, so there's still much to learn about it. In the study, the researchers note the possibility that this crocodylomorph didn't take to the land but used its hind legs to propel itself through waterways.</p><p>Not all paleontologists agree with the study's conclusions. Phil Manning, a paleontologist at the University of Manchester, who was not part of the research, <a href="https://www.bbc.com/news/science-environment-53011567" target="_blank">told the BBC</a><u> </u>he found the trace fossils interesting but didn't think a crocodilian was capable of producing them.</p><p>"Look at any videos of living crocs and the rotation of their feet when they're galloping: it's outwards, not inwards towards the midline of the trackway. Just from their orientation, it looks more like some kind of dinosaurian track-maker to me. But whether it's a croc - unfortunately, we just don't have the fossil bones to tell us," he said.</p>
Plenty of crocs in the fossilized sea<p>If you had your heart set on a land-roaming, bipedal crocodile, don't be disappointed. The ancient world was filled with enough strange and eerie crocodylomorphs to fill many a nightmarish menagerie.</p><p>In 2015, for example, paleontologists discovered a crocodile relative in North Carolina. This 9-foot-long apex predator also walked on two feet and ruled its Pangaean stomping grounds until the Triassic-Jurassic extinction event ended its reign. Paleontologists christened this species <em>Carnufex carolinensis</em>, or the "<a href="https://www.pbs.org/newshour/science/newly-discovered-bipedal-crocodile-ancestor-terrorized-pre-dinosaur-world" target="_blank">Carolina Butcher</a>."</p><p>There's also evidence for crocodiles that <a href="https://www.youtube.com/watch?v=qruxOVmSfyY" target="_blank">snatched sauropods from the water's edge</a>, crocodiles that bounded through ancient forests <a href="https://www.youtube.com/watch?v=QmdcewIjXi0" target="_blank">on hooves</a>, and crocodiles that enjoyed <a href="https://www.smithsonianmag.com/smart-news/ancient-crocodiles-would-have-ordered-salad-180972518/" target="_blank">leafy flexitarian diets</a>. Even their modern relatives continue to surprise us, such as their <a href="https://www.wired.com/2014/02/crocodiles-can-climb-trees/" target="_blank">surprisingly agile tree-climbing abilities</a>.</p><p>So while these ancient creatures may be extinct, they continue to evolve in our imaginations. We'll have to see what science has in store for <em>Batrachopus grandis</em> as we discover more about it. </p>
These Jurassic predators resorted to cannibalism when hit with hard times, according to a deliciously rare discovery.
- Rare fossil evidence of dinosaur cannibalism among the Allosaurus has been discovered.
- Scientists analyzed dinosaur bones found in the Mygatt-Moore Quarry in western Colorado, paying special attention to bite marks that were present on 2,368 of the bones.
- It's likely that the predatory carnivore only ate their already-dead peers during times when resources were scarce.
Desperate times call for cannibalism<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="cc909d1235ba9e4e5149f7e3580c8568"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/Y2ODPFiksBE?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>While scavenging and even cannibalism is relatively common among today's predators, the Allosaurus probably didn't eat their peers as a staple meal. According to Stephanie Drumheller, the study's lead author, they were likely driven to turn to cannibalism as a last resort when times were scarce in food supply. </p> <p>"Big theropods like Allosaurus probably weren't particularly picky eaters, especially if their environments were already strapped for resources.'' said Drumheller, a paleontologist in the University of Tennessee, Knoxville's Department of Earth and Planetary Sciences, <a href="https://www.eurekalert.org/pub_releases/2020-05/p-ise052120.php" target="_blank">in a statement</a>. "Scavenging and even cannibalism were definitely on the table."</p><p>The Mygatt-Moore Quarry is home to thousands of dinosaur bones dating back to the late Jurassic period, somewhere in the ballpark of 150 million years ago. When the quarry was at its prime, it was thriving with lush vegetation making it a cushy home for many large dinosaur species, including the long-necked lizard <a href="https://www.livescience.com/25093-apatosaurus.html" target="_blank">Apatosaurus</a>. The new study suggests, however, that at some point this dino sanctuary fell on some hard times, which forced local carnivores to scavenge for bits of meat from the picked-over carcasses of dead dinosaurs.</p>
Study Findings<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzM2NDg4MS9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTYwODAxOTMzOX0.X586xL4Ci-v4fwAaKZJAf7QOp7EANWKy9ScFV49l-us/img.png?width=980" id="992a1" class="rm-shortcode" data-rm-shortcode-id="acecfb3761e4e8b41e02b29bfd62452c" data-rm-shortcode-name="rebelmouse-image" />
Fig 4. Dry season at the Mygatt-Moore Quarry showing Ceratosaurus and Allosaurus fighting over the desiccated carcass of another theropod.
Illustration by Brian Engh (dontmesswithdinosaurs.com)<p>The researchers examined the bite marks on 2,368 dino bones from the quarry. Noting the width, depth, and pattern of the bite marks, the team was able to trace the chomp marks on the prey back to specific dinosaur species. Of those bones, 684, or 29 percent, were marked with at least one theropod bite. Many of those marks were imprinted by serrated teeth, suggesting to the researchers that Allosaurus (the most common theropod among the quarry's fossils) did a majority of the biting.</p><p>Allosaurus tended to feast mostly on herbivores. Yet, 17 percent of their bite victims were other theropods. That included some fellow Allosauruses, making this the first solid chunk of evidence of cannibalism in the species; a deliciously novel discovery. Interestingly, however, most of the bite marks that the scientists examined didn't appear to be killing wounds. More than half of all bite-marks found on the victim were on bony parts with little meat like fingers, toes and spinal columns. Not exactly the cut of meat a hunter with first-dibs would choose, suggesting that they were scavenging for the bare scraps. </p><p>Ultimately, these fossils tell a miserable story of dinosaurs down on their luck, left with no choice but to scrounge for measly scraps of meat off their own kin's rotting carcasses. </p>
Researchers think they know how a group of ancient sloths, who died thousands of years ago in Ecuador, met their untimely end.
- Evidence collected from an ancient boneyard in Ecuador suggests that a group of 22 ancient giant sloths died in a wallow of their own feces.
- Other mammals, such as a deer, a horse, an elephant-like creature called a gomphothere, and another species of ground sloth were identified at the site.
- The fate of the sloths parallels that of modern hippos who can become lethally poisoned in times of drought when the feces to water ratio shifts in their watering holes.
Discoveries from an ancient boneyard<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="0745aba719f914d2113ab181ef8201b8"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/vDCk0Uma2m4?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>An assemblage of 677 bones, 575 of which belonged to <em>E. laurillardi</em>, were found on this site in the Santa Elena peninsula in Ecuador. Other mammals, such as a deer, a horse, an elephant-like creature called a gomphothere, and another species of ground sloth were identified. Analysis of <em>E. laurillardi</em>'s bones reveal that the sloths likely died around the same time, evidenced by the lack of sediment separating them. They were also part of a multigenerational group, including at least 15 adults, one teen, and six children. This arrangement of remains and the range of ages indicates a mass mortality event, according to the researchers.</p><p>Giant ground sloths were once one of the most common large vertebrates living in the Americas. <a href="https://advances.sciencemag.org/content/5/2/eaau1200?rss=1" target="_blank">Prior research</a> indicates that the species, which can reach lengths of 19 feet, were widely distributed across the region ranging from southern Brazil to North America's Gulf and Atlantic coasts. We also know that they died out 11,000 years ago. But little has been known about their behavior and social structure, which is why this latest find is so exciting.</p><p>While modern sloths are solitary creatures, the paper suggests <em>E. laurillardi</em> were rather gregarious creatures who congregated near water. Tanque Loma was probably once a marshy watering hole where the sloths cooled off, bathed, and quenched themselves similar to warthogs and hippopotamus populations today. </p>
Clues point to a crappy death<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzI4MzE2My9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyODU1NzY3OX0.91lo89Xr_jBdsvWSkKTbHwNOJWv7jBnd7YuA4q6Z1_U/img.jpg?width=1245&coordinates=0%2C326%2C0%2C0&height=700" id="78782" class="rm-shortcode" data-rm-shortcode-id="daf9283b05bad90707373531acf5a906" data-rm-shortcode-name="rebelmouse-image" alt="pod of hippos" />
Photo Credit: Jeff Griffith / Unsplash<p>Prior analysis suggested that the asphalt on the site seeped into the sloths' gravesite after the bones had already been deposited, thus ruling out death by asphalt poisoning. Death by volcano or other natural disaster is also unlikely because the sediments do not contain ash or charcoal. And because the sloths across a full range of age groups are present, their death probably wasn't caused by disease or a predatory attack, either. In those cases, there would be an overrepresentation of old and young.</p><p>Rather, the researchers believe the sloths died another way.</p><p>"Taking observations from modern megafaunal ecosystems as an analogue, we suggest that this death event could have resulted from drought and/or disease stemming from the contamination of the wallow, paralleling situations observed among hippopotamus populations in watering holes on the present-day African savannah," write the researchers in the paper.</p><p>The scientists suspect that the fate of some hippopotamus groups may point to what happened to these 22 ancient giant sloths. Hippos are apparently <a href="https://www.sciencealert.com/hippopotamus-faeces-causes-water-hypoxia-kills-fish" target="_blank">prolific poopers</a>. So much so that the amount of their waste can change the chemistry of water they spend their days in to the point of sometimes killing all the fish. It can even, sometimes, kill the hippos in times of drought when the feces to water ratio shifts.</p><p>"Based on the data from this study, a modern analogue to the Tanque Loma <em>E. laurillardi</em> assemblage may be hippopotami, which congregate in large numbers at water sources where they spend most of their time submerged to protect themselves against heat, sun and insects," <a href="https://www.sciencedirect.com/science/article/abs/pii/S003101821930447X" target="_blank">the researchers wrote</a>. "In times of drought, as these water sources begin to dry up, surrounding vegetation disappears and the wallows become increasingly polluted with hippopotamus faecal material, causing significant detrimental impacts on the watershed ecosystem." </p><p>Besides bones, the team found plant material in <em>E. laurillardi</em>'s fossil bed. Interestingly, this was not living plant material—it had been digested and excreted. This supports the theory that the ancient sloths met their unfortunate demise in a slop of their own feces.</p>
Non-avian dinosaurs were thought terrestrially bound, but newly unearthed fossils suggest they conquered prehistoric waters, too.
Unearthing a mystery in the desert<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzE4MDU1OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyNzI1NTExM30.1L90N5rrjAiYqBzRa72_b3hmP8Bq20MdZ3KtdfSgUTg/img.jpg?width=1245&coordinates=0%2C24%2C0%2C262&height=700" id="765d6" class="rm-shortcode" data-rm-shortcode-id="45a87235d3fe79b339ade44f58f9818c" data-rm-shortcode-name="rebelmouse-image" />
Stromer's holotype of his original Spinosaurus specimen.
A digital resurrection<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzE4MDU1OS9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTU5NTM2MTExOX0.YuUzxvnm_mHQYTvH2e_Xjq4pKjE_U7R5HEf-xc1TfVc/img.png?width=1245&coordinates=92%2C0%2C93%2C0&height=700" id="c2e6e" class="rm-shortcode" data-rm-shortcode-id="b58ca0abb324db9a0fd7851490615a89" data-rm-shortcode-name="rebelmouse-image" />
An illustration of a Spinosaurus skeleton with its thinner, more traditionally therapod-like tail.