Wikipedia:Reference desk/Archives/Science/2021 October 4

= October 4 =

How can a archaeologist tell whether dinosaur is carnivorous or herbivores?
How can a archaeologist tell whether dinosaur is carnivorous or herbivores just by seeing the skeleton? Rizosome (talk) 00:29, 4 October 2021 (UTC)
 * Probably by the nature of the teeth. ←Baseball Bugs What's up, Doc? carrots→ 00:58, 4 October 2021 (UTC)
 * See Biting DuncanHill (talk) 01:04, 4 October 2021 (UTC)


 * One indirect clue is that there are a lot more fossil specimens of plant-eaters such as Hadrosauridae, then there are of carnivores. Lots more potential prey than predators. ←Baseball Bugs What's up, Doc? carrots→ 03:11, 4 October 2021 (UTC)
 * That is not a clue that can be used when seeking to classify a given dinosaur species, and an unnecessarily confusing comment. --Lambiam 08:59, 4 October 2021 (UTC)


 * Wouldn't this be a paleontologist rather than an archeologist? -- Ross Burgess
 * Or even a Dentopaleontologist?? . Martinevans123 (talk) 09:03, 4 October 2021 (UTC)
 * palaeodontology —Tamfang (talk) 00:45, 8 October 2021 (UTC)


 * As DuncanHill wrote, the classification is primarily based on the type of teeth found in fossils. For example, paleontologists suspect that dinosaurs in the genus Troodon were omnivores based on serrations on their teeth. The morphology (shape) of the jaws can be a further indication. Often, the classification (which can also include more specific classifications such as frugivore, insectivore and piscivore) is tentative, and different paleontologists may favour different hypotheses. --Lambiam 09:21, 4 October 2021 (UTC)


 * FYI, archeology is generally about humans, and paleontology is general about non-humans. ←Baseball Bugs What's up, Doc? carrots→ 09:33, 4 October 2021 (UTC)
 * Specifically, paleontology "is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present)".
 * Archaeology is the study of "human prehistory and history, from the development of the first stone tools at Lomekwi in East Africa 3.3 million years ago up until recent decades".
 * Alansplodge (talk) 09:53, 4 October 2021 (UTC)


 * Note that the vegetation at the time was different, dominated by pine trees and conifers which are much tougher to chew on and digest than plants herbivores of today eat. Count Iblis (talk) 17:34, 4 October 2021 (UTC)
 * Never thought of that. Crazy. How did their digestive tracts handle all the sharp points? Imagine Reason (talk) 18:05, 4 October 2021 (UTC)
 * Lots of grinding before swallowing. Mikenorton (talk) 20:43, 4 October 2021 (UTC)
 * This Gastrolith may have helped in digestion as well. MarnetteD&#124;Talk 22:39, 4 October 2021 (UTC)
 * ... or else Fred and Wilma just took Dino downtown to get some tasty Pterodactyl ribs?? Martinevans123 (talk) 22:02, 4 October 2021 (UTC)
 * Nice one . We took my Mom to The Fort (Morrison, Colorado) for her 70th birthday. She ordered the buffalo ribs and when they brought them out those huge ribs next to my tiny Mom immediately brought that scene to mind :-P MarnetteD&#124;Talk 22:39, 4 October 2021 (UTC)

What is it?
Hi, can anyone identify this insect? It was seen on a Buddleia bush in the south of England. ITookSomePhotos (talk) 17:33, 4 October 2021 (UTC)
 * Some form of hover fly, mimicking a wasp of hornet, perhaps a Volucella zonaria. Mikenorton (talk) 20:40, 4 October 2021 (UTC)
 * Thanks, yes it really does look very similar to the picture at that article. I see plenty of the smaller-size hoverflies, but I didn't realise any grew so big. ITookSomePhotos (talk) 21:06, 4 October 2021 (UTC)
 * Hornet mimic hoverfly says that it's "the largest hoverfly species in the UK" and "has become more common in Southern England in recent years... particularly prevalent in urban areas". Alansplodge (talk) 12:01, 5 October 2021 (UTC)

Slightly off-topic but speaking of buddleia, I pulled my van up to a house in the north of England a couple of weeks ago and a buddleia bush exploded with butterflies of every size and colour. After I made my delivery they'd landed again so I crept up to the bush and recorded a video to show my mother. There were perhaps a hundred or more butterflies. I haven't seen that many in one place since the 1980s, and once read that their populations had declined by a factor of 10,000 over the years. It was wonderful to see. Apparently they like buddleia. nagualdesign 13:13, 8 October 2021 (UTC)


 * It's worth knowing that buddleia is an invasive species and should be carefully controlled in the garden and that it only provides nectar for adult butterflies - there are actually better alternatives if you want to attract butterflies - see this rspb link. Mikenorton (talk) 13:44, 8 October 2021 (UTC)
 * Aren't all butterflies adults? A young butterfly is a caterpillar, and they don't feed on nectar. Perhaps I've misunderstood your comment. nagualdesign 21:12, 9 October 2021 (UTC)


 * The really invasive Buddleja (note the correct spelling - the powers-that-be changed it a few years ago) is B. davidii, and even then I've found that some of the cultivars are less inclined to seed everywhere. From my experience I would say that none of the plants listed on that RSPB page is a particular butterfly attractant - maybe lavender a little bit, but it's mostly bees that go for lavender. Two plants that really are liked by butterflies as nectar sources are Verbena bonariensis and Hylotelephium spectabile (formerly Sedum spectabile), though these aren't shrubs. PaleCloudedWhite (talk) 19:49, 8 October 2021 (UTC)
 * Yes, a lot of houses in and around Lancaster, Morecambe, Carnforth and Grange-over-Sands have lavender growing in their gardens and bees absolutely love it. Thanks for posting the information on which plants butterflies like. Hopefully there will be a few avid gardeners and wildlife enthusiasts who take note. nagualdesign</b></b> 21:04, 9 October 2021 (UTC)

Is the fuel used for the Space Shuttle Challenger still used today?
I have read, or attempted to read, many articles on this subject, but I cannot figure this out. Thanks, Krok6kola (talk) 23:31, 4 October 2021 (UTC)
 * The fire coming out of the actual shuttle is just liquid hydrogen and oxygen, still used today. I think there's still a rocket sending men into orbit with kerosene and liquid oxygen (which is almost century old rocket oxidant, first distilled from air in the 1800s). High technology is not required, in the realm of fuel exoticness. Sagittarian Milky Way (talk) 00:28, 5 October 2021 (UTC)
 * My guess is that the OP is asking about the fuel used in the solid-rocket booster, since that was the bit that exploded. --Trovatore (talk) 00:39, 5 October 2021 (UTC)
 * Yes, that is what I am asking. Krok6kola (talk) 01:31, 5 October 2021 (UTC)
 * Our article on the Space Shuttle Solid Rocket Booster has a section called "Propellant", which explains that it used aluminum powder as the fuel, with an ammonium perchlorate oxidizer and an iron oxide catalyst, with some other ingredients. This is an ammonium perchlorate composite propellant; that article has a section on "Uses", but unless I missed it does not say whether the specific composition used in the Space Shuttle is still in use. --Trovatore (talk) 01:40, 5 October 2021 (UTC)
 * Not in use for the Space Shuttle, as it is retired, but used essentially unchanged (just more of it) for the boosters of the Shuttle derived SLS. EDIT: OK, I suppose technically that's not in use today, as it hasn't had it's first launch yet, but it's close enough Fgf10 (talk) 07:29, 5 October 2021 (UTC)
 * The cause of the disaster was a failing seal leading to a burn-through sending a flame to the external tank. This led to the explosion of the external tank, when the already compromised liquid hydrogen tank was pushed into the liquid oxygen tank. The original failure might have led to disaster with any type of potentially explosive propellant, but the boosters themselves did not explode. They remained mostly intact, except for a burn-through in one of the pair. (See Timeline of STS-51-L.) --Lambiam 05:03, 5 October 2021 (UTC)
 * I have already read all that and already knew the above. I learned (via Netflix) that the Russians do no use solid fuel boosters. (Is that true?) I understand that the average Ph.D. in a science-based area (me), but not "hard" science, does not have the training to understand your articles on these subjects. And I still do not understand what Ammonium perchlorate composite propellant is from your articles, not for lack of trying. But thank you for taking the time to answer. Krok6kola (talk) 08:12, 5 October 2021 (UTC)
 * Perhaps you could add an item on the article's talk page about intelligibility, but note that the whole article has "multiple issues" and is a work-in-progress. Alansplodge (talk) 11:56, 5 October 2021 (UTC)
 * It isn't a great article, but really, not being able to read it and say what the stuff is? It isn't that bad.  All you need is some very basic chemistry knowledge (my last chem class was as a freshman in college), and if you don't have that, then I'm not sure what sort of answer to "what the stuff is" you could understand anyway. --Trovatore (talk) 15:57, 5 October 2021 (UTC)
 * I don't have an academic degree, let alone a PhD, but I experienced no problem understanding . IMO the article explains this quite clearly. --Lambiam 09:16, 6 October 2021 (UTC)
 * Just to be very clear: "The cause of the disaster" were inexpert decisions made in advance, that led to a "failing seal". --87.147.178.162 (talk) 09:10, 5 October 2021 (UTC)
 * Or perhaps the cause was animals crawling ashore God knows how many million years ago. If they had just staid in the water, the disaster would not have happened. --Lambiam 09:09, 6 October 2021 (UTC)
 * No, the failure of the O-ring was a direct consequence of launching in colder than recommended weather, presumably the decisions 87.147 refers to. Those are highly relevant to the accident, and mentioning them certainly doesn't deserve the mockery you gave them. Fgf10 (talk) 16:10, 6 October 2021 (UTC)
 * The failing seal was the proximate cause. It is too simple to state that the decisions were the cause, as if this is the only correct answer. We still don't know why precisely Aunt Minnie is in a hospital.

There is a whole book, The Challenger Launch Decision by sociologist Diane Vaughan, that studied the organizational processes leading up to the explosion. It was not just the cold weather launch, but the normalization of deviance stretching over many launches leading up to it. The O-ring that burned through on the doomed launch had burned partway through on earlier launches, but that was not seen as a failure since the Shuttle didn't explode. In fact it was not intended to burn at all, and should have been fixed as soon as any burn-through was noticed. The second half of Richard Feynman's memoir What Do You Care What Other People Think? discusses this at length. Feynman was on the commission that investigated the explosion and wrote up his experiences. He was the one who called public attention to the effects of cold weather on the O-ring. As for rocket propellant, yes, I am pretty sure the aluminum/rust mix used in the Shuttle solid rocket boosters is a standard thing still used in solid rockets. However, I also believe (would have to check to be sure) that the Shuttle was the only US manned space launcher to use solid rocket boosters. The rest used only liquid fuels, which have higher specific impulse and can be throttled, but are more mechanically complicated. I do believe some Soviet manned launchers used solid boosters. 2602:24A:DE47:B8E0:1B43:29FD:A863:33CA (talk) 08:41, 8 October 2021 (UTC)