Wikipedia:Reference desk/Archives/Science/2023 July 19

= July 19 =

Magnesium Sulphate
Last year, I bought some magnesium sulphate paste for removing splinters. Now it has separated into a hard, crystalline, mass and some clear liquid resembling glycerine. Is there any way of returning it to a paste or do I have to buy some more? Alansplodge (talk) 10:52, 19 July 2023 (UTC)
 * Magnesium Sulphate Paste is literally just magnesium sulphate and glycerine, with a small amount of phenol. Here is a typical ingredient list, but I've checked several others, and that's what it is.  It hasn't "gone off" or anything, the magnesium sulphate has just settled out of the suspension (which is what a "paste" generally is, from a chemistry point of view).  Depending on how much effort you want to put in (vis a vis the cost of just buying more) you should be able to just remix the ingredients.  -- Jayron 32 11:36, 19 July 2023 (UTC)
 * Thanks Jayron. The problem is that the solid part has the consistency of concrete and has so far resisted my remixing efforts. Would heating it help? Alansplodge (talk) 11:42, 19 July 2023 (UTC)
 * Possibly, gentle heating would help. IIRC, magnesium sulphate is usually a fairly well-hydrated crystal, and gentle heating may help release some of the "waters of hydration", possibly enough to dissolve it slightly and help break it up (see Epsom salt).  If that doesn't work, perhaps something like a kitchen blender or food processor may help?  If you don't have anything like that, I'm at a loss.  -- Jayron 32 11:48, 19 July 2023 (UTC)
 * Bingo! I pinged it in the microwave - worked like a charm. Many thanks. Alansplodge (talk) 12:50, 19 July 2023 (UTC)

Evolution of birds from dinosaurs
As far as I'm aware, the current scientific consensus is that modern birds evolved from the tiny number of dinosaurs that survived the Chicxulub impact. However, it is somewhat unclear to me - did birds, as we know them now exist *before* the meteorite hit, or did they emerge later? At school, I was taught that all mammals evolved from a small number of tiny rat-like creatures (in terms of body form) that somehow survived the apocalypse - and that all birds evolved from a small number of tiny velociraptor-like creatures (in terms of body form) that somehow survived the apocalypse - but I think from my readings that this is inaccurate now? Iloveparrots (talk) 21:50, 19 July 2023 (UTC)
 * See the related articles Origin of birds and Evolution of birds. The evolutionary events that gave rise to the early birds within maniraptoran theropods and the origin of bird flight are disputed questions. Philvoids (talk) 22:35, 19 July 2023 (UTC)
 * Today's birds form the class Aves, which is a subset of the clade Ornithurae. This clade also includes two extinct genera of bird-like reptilians. --Lambiam 22:39, 19 July 2023 (UTC)
 * Birds evolved before the end-Cretaceous extinction event, although exactly how much before depends on how you define "birds". If "birds" means "the most recent common ancestor of all living birds and all of it descendants", then birds first appeared some time in the Cretaceous.  If "bird" is defined more broadly to include Archaeopteryx, then they evolved in the Jurassic. Iapetus (talk) 12:30, 20 July 2023 (UTC)
 * To build on the excellent answers above, and to directly answer the question "did birds, as we know them now exist *before* the meteorite hit, or did they emerge later?" four clades of birds are believed to have existed prior to the Cretaceous–Paleogene extinction event that killed off the non-avian dinosaurs, which is to say that the "most recent common ancestor" of all modern birds predates the extinction event by some time. Roughly speaking, those clades are the "big fat running birds" of the ostrich-emu-cassowary type,  "waterfowl" like ducks and geese, "groundfowl" like chickens and turkeys and peafowl, and "everything else".  It is thought that these divisions among birds (or bird-like dinosaurs or whatever term you wish to use) existed prior to the extinction event.  You can find a partial list of such birds at Category:Mesozoic birds.  Also as noted, the exact nature of mesozoic bird evolution is unresolved; there are several competing theories, but all we do know is that whatever happened to give us birds, it certainly happened prior to the extinction event that took out the rest of the dinosaurs.  -- Jayron 32 12:31, 20 July 2023 (UTC)
 * As for mammals, see Evolution of mammals. --User:Khajidha (talk) (contributions) 13:16, 21 July 2023 (UTC)

GF's question:
My girlfriend wants to know what is the world's largest penis, and I'm NOT talking about porn. (She caught me editing on Wikipedia and got curious about Wikipedia as well ) I'm talking about human penises. 😺😘🥰 Nuclear Sergeant (talk) 22:57, 19 July 2023 (UTC)
 * See the article Human penis size and a claim of Jonah Falcon. Philvoids (talk) 01:46, 20 July 2023 (UTC)
 * Or this: ←Baseball Bugs What's up, Doc? carrots→ 05:59, 20 July 2023 (UTC)
 * According to Wikipedia, the penis on a right whale can be up to 2.7 m (8.9 ft) Shantavira|feed me 07:59, 20 July 2023 (UTC)