WEBVTT - What Can a Cache of Pterosaur Eggs Teach Us? 0:00:02.040 --> 0:00:06.920 Welcome to brain stuff from how stuff works. Hey, they're 0:00:06.960 --> 0:00:10.319 brain stuff, Lauren bobil bomb here. Flight is a hard 0:00:10.360 --> 0:00:14.080 thing to master. The vast majority of vertebrates can walk, swim, 0:00:14.200 --> 0:00:16.440 or do both, but in the history of life on 0:00:16.480 --> 0:00:19.680 this planet, only three groups of backboned animals have ever 0:00:19.760 --> 0:00:23.239 evolved the ability to fly. Early bats acquired the skill 0:00:23.360 --> 0:00:26.560 roughly fifty two million years ago. Feathered dinosaurs began to 0:00:26.600 --> 0:00:30.040 experiment with flight back in the Jurassic period. Incidentally, you 0:00:30.080 --> 0:00:33.800 probably know of their descendants today as birds. Yet while 0:00:33.880 --> 0:00:36.400 birds and bats are still around, the animals that first 0:00:36.479 --> 0:00:40.320 pioneered vertebrate flight are long gone. That's because two hundred 0:00:40.320 --> 0:00:43.279 and twenty eight million years ago, a flying plade of 0:00:43.360 --> 0:00:48.160 reptiles evolved. These were the pterosaurs. Though Hollywood often mislabels 0:00:48.159 --> 0:00:51.880 them as dinosaurs, they actually represented a separate, contemporaneous group. 0:00:52.720 --> 0:00:55.320 For more than a hundred and sixty million years, dinosaurs 0:00:55.320 --> 0:00:58.320 and pterosaurs lived side by side. It was an exciting 0:00:58.360 --> 0:01:01.320 time to be an aeronaut. During their reign, the pterosaurs 0:01:01.400 --> 0:01:05.560 diversified like crazy. Some species would be comparable to sparrows 0:01:05.560 --> 0:01:08.680 in size. Others had wingspans of thirty six feet that's 0:01:08.680 --> 0:01:11.840 eleven meters or more, making them the largest flying animals 0:01:11.840 --> 0:01:15.039 of all time. Then, sixty six million years ago, the 0:01:15.080 --> 0:01:18.200 pterosaurs succumbed to the same mass extinction that wiped out 0:01:18.240 --> 0:01:22.560 all non avian dinosaurs. In seventeen eighty four, Italian naturalist 0:01:22.600 --> 0:01:25.199 Cosmo Collini became the first person to write a formal 0:01:25.280 --> 0:01:28.920 scientific description of a pterosaur skeleton. At the time, he 0:01:29.000 --> 0:01:31.400 thought this strange looking animal was some kind of deep 0:01:31.440 --> 0:01:35.000 sea creature. But thanks to hard working paleontologists, we've learned 0:01:35.040 --> 0:01:38.200 a great deal about these winged wonders. Nonetheless, there are 0:01:38.200 --> 0:01:41.520 still some large gaps in our knowledge. One big mystery 0:01:41.560 --> 0:01:45.080 involves the early lives of young pterosaurs. The first confirmed 0:01:45.200 --> 0:01:48.760 dinosaur nest was unearthed in ninety three. Since then, fossil 0:01:48.800 --> 0:01:51.720 hunters have excavated thousands of dino exit sites all over 0:01:51.720 --> 0:01:56.040 the world. Yet pterosaur eggs are considerably rarer. None whatsoever 0:01:56.040 --> 0:01:58.920 were discovered until two thousand four, when two appeared in 0:01:59.000 --> 0:02:02.279 China and a third showed up in Argentina. In eleven, 0:02:02.480 --> 0:02:04.600 a fourth egg was found next to the skeleton of 0:02:04.600 --> 0:02:07.280 its presumed mother, an adult animal from the genus Darwin, 0:02:07.360 --> 0:02:11.000 a terrorist three years later, and another Argentinian egg emerged, 0:02:11.040 --> 0:02:15.079 along with five additional Chinese specimens. So until very recently, 0:02:15.200 --> 0:02:18.280 the global scientific community hadn't found enough terrasaur eggs to 0:02:18.320 --> 0:02:22.440 fill a standard egg carton, but paleontologists just hit the motherload. 0:02:22.800 --> 0:02:25.799 In the December seventeen issue of the journal Science, a 0:02:25.919 --> 0:02:28.680 Chinese research team announced the discovery of a new site 0:02:28.680 --> 0:02:31.680 in China's Gobi Desert containing at least two hundred and 0:02:31.720 --> 0:02:36.120 fifteen pterosaur eggs. Sixteen preserved embryos were found there as well, 0:02:36.320 --> 0:02:40.040 along with some skeletons from hatchling, juvenile, and adult pterosaurs. 0:02:40.680 --> 0:02:43.119 These eggs are roughly a hundred and twenty million years 0:02:43.160 --> 0:02:47.320 old and were laid by Hammatteris tiensnsis a crusted toothy 0:02:47.400 --> 0:02:50.399 species with an eleven foot wingspan that's about three point 0:02:50.440 --> 0:02:54.000 three meters. Terrastaur experts are still trying to assess where 0:02:54.000 --> 0:02:56.960 it belongs on the family tree. One such authority is 0:02:57.000 --> 0:03:00.080 paleontologist David Hone, who told us in an email that 0:03:00.160 --> 0:03:03.880 Hama RAS's closest relatives were most likely various groups of 0:03:03.960 --> 0:03:07.200 terrasaurs known for being ocean going or at least coastal 0:03:07.240 --> 0:03:10.240 foragers in terms of lifestyle, He says that these animals 0:03:10.240 --> 0:03:14.520 would have behaved like today's gulls and albatrosses. The newfound 0:03:14.520 --> 0:03:16.960 bounty of eggs was recovered by a team representing the 0:03:17.000 --> 0:03:20.400 Beijing based Chinese Academy of Sciences. Most of the shelled 0:03:20.400 --> 0:03:22.840 treasures were embedded in a sandstone block that may be 0:03:22.960 --> 0:03:25.240 hiding even more clutches that have yet to be revealed. 0:03:25.919 --> 0:03:28.200 One reason why this find is so spectacular has to 0:03:28.240 --> 0:03:31.960 do with the fragility of terrasaur egg shells. Like modern chickens, 0:03:32.080 --> 0:03:35.800 extinct dinosaurs laid hard shelled eggs. Contrast these with the 0:03:35.800 --> 0:03:39.240 eggs of present day snakes, whose shells are thin, soft, pliable, 0:03:39.400 --> 0:03:42.880 and have the texture of old parchment. Terrasaur eggs resembled 0:03:42.880 --> 0:03:46.600 the ladder, a fact confirmed by previous discoveries. Because their 0:03:46.600 --> 0:03:49.000 shells were so soft, these rare eggs tend to get 0:03:49.160 --> 0:03:52.160 squitched flat by the forces of fossilization. Yet the ones 0:03:52.200 --> 0:03:54.800 that this new Chinese site were preserved in three dimensions. 0:03:55.480 --> 0:03:59.480 The discovery's implications are still open to debate. Chinese Academy 0:03:59.480 --> 0:04:03.240 of Sciences paleontologist Shallon Wang was the lead author of 0:04:03.280 --> 0:04:06.040 the paper in the journal Science, which announced this big find. 0:04:06.360 --> 0:04:08.680 In it, he and his co authors suggest the site 0:04:08.800 --> 0:04:11.920 may have a lot to say about terrasaur parenting. As 0:04:11.920 --> 0:04:14.480 Whanging and his colleagues point out, some of the embryo's 0:04:14.520 --> 0:04:18.839 lack teeth and their wingbones seem underdeveloped. The paleontologists think 0:04:18.920 --> 0:04:21.960 this could mean that newly hatched Hamma terrists could neither 0:04:22.000 --> 0:04:25.000 fly nor eat solid food. Thus they would have had 0:04:25.040 --> 0:04:28.800 to depend on their parents for protection and sustenance. Other 0:04:28.800 --> 0:04:32.279 scientists have disagreed with that conclusion. In present day reptiles, 0:04:32.320 --> 0:04:35.200 teeth are one of the last things embryos developed, so 0:04:35.400 --> 0:04:38.359 while these developing pterosaurs were toothless, they might still have 0:04:38.400 --> 0:04:42.440 grown some choppers before hatching. Also, according to Michael Habib, 0:04:42.600 --> 0:04:45.760 a pterosaur specialist at the University of California, the fetal 0:04:45.800 --> 0:04:48.760 wings appeared quite robust, meaning the newborns might have been 0:04:48.760 --> 0:04:51.920 able to start flying right away. A point of consensus 0:04:51.920 --> 0:04:55.760 among paleontologists, though, is that pterosaurs probably didn't brood their 0:04:55.760 --> 0:04:58.520 eggs like present day birds. For one thing, as Hone 0:04:58.560 --> 0:05:01.200 told us, the extinct reptile simply could not sit like 0:05:01.279 --> 0:05:05.280 birds due to the anatomical differences. Also, While terrasaurs were 0:05:05.279 --> 0:05:08.840 coated with fuzzy stuff, they lacked feathers, which roosting avians 0:05:08.960 --> 0:05:12.320 used to keep their clutches nice and warm. Another leading 0:05:12.360 --> 0:05:15.880 expert in modern terrasaur science, one S. Christopher Bennett of 0:05:15.960 --> 0:05:20.000 Fort Hayes State University in Kansas, agrees. He said via email, 0:05:20.320 --> 0:05:23.000 there's no evidence and no reason to think that pterosaurs 0:05:23.040 --> 0:05:27.200 incubated their eggs, or rather, they probably deposited them in sands, soils, 0:05:27.279 --> 0:05:31.279 or vegetable matter like modern reptiles. In the past, Bennett 0:05:31.320 --> 0:05:34.280 has championed the idea that at least some terrasaurs formed 0:05:34.360 --> 0:05:37.760 nesting groups near environments suitable for the hatchlings to feed 0:05:37.760 --> 0:05:41.200 and grow safely. He feels the new Hemiiturus site may 0:05:41.279 --> 0:05:44.040 lend some credence to that notion, a sentiment shared by 0:05:44.080 --> 0:05:47.440 Weighing and his co authors. Bennett added careful excavation of 0:05:47.600 --> 0:05:50.800 terrasaur egg deposits could certainly provide evidence as to whether 0:05:50.839 --> 0:05:54.920 eggs were buried and whether terrasaurs reused nesting sites year 0:05:54.920 --> 0:06:03.279 after year. Today's episode was written by Mark Vancini and 0:06:03.320 --> 0:06:05.960 produced by Tristan McNeil. For more in this and lots 0:06:06.000 --> 0:06:09.119 of other thunders topics, visit our home planet, how stuff 0:06:09.120 --> 0:06:21.160 works dot com.