Prehistoric animals/dinosaurs we know the gender/dimorphism of

[Stegotyranno420]

So far i only know about Male Protoceratops being more robust than females, and many of closely related mammals of the past having similar ways to their modern versions(lions, elephants, dogs)

Im also aware of the myth about female dinosaurs being larger than males
And I know about the debate/speculated notion of male stegosaurus being larger and having more larger plates.

So besides all of that mumbo jumbo what else do we know about this subject.

[TethysaurusUK]

Motani (2021) may have determined that some dinosaur taxa show sexual dimorphism (Allosaurus fragilis, Hesperosaurus mjosi and Protoceratops andrewsi) along with the nothosaur Keichousaurus hui. Allosaurus fragilis (likely extending to all Allosaurus species) potentially exhibits dimorphic femoral head:femoral length ratios. i]Hesperosaurus mjosi[/i] shows dimorphism in the height and width of their plates. Protoceratops andrewsi is dimorphic in regards to the size of the external nares, nasal and frill elements. Plateosaurus sp. shows unclear dimorphism, and was rejected in the hypothesis. Keichousaurus hui males appear to have longer hindlimbs. However, this study does note this data only partly shows dimorphism and there are potentials for new research to show no dimorphism.

https://academic.oup.com/zoolinnean/advance-article/doi/10.1093/zoolinnean/zlaa181/6105009?login=true

Motani, R., 2021. Sex estimation from morphology in living animals and dinosaurs. Zoological Journal of the Linnean Society.

[Stegotyranno420]

Please im just a young boy, im not comfortable using the word sex, and isn't gender and sex the same thing? Im not too good on the subject, I just wanted to ask like who was bigger and different in features not get into the "dirty" stuff as I usually stray away. I hope you can understand where I'm coming from and im sorry if I said something innacurate
@TethysaurusUK thanks cor info

[Libraraptor]

The term is "Sexual dimorphism". Both sex and belonging to a sex are nothing dirty and indecent at all.

[Stegotyranno420]

The term is "Sexual dimorphism".

I understand that. I just prefer using dimorphism over S**ual Dimorphism. Pretty sure its interchangeable.
Anyways, moving on, are there any other examples?

[Stegotyranno420]

Wait, so can you correct me if I'm wrong: s*x is what they are, and gender is what they THINK they are? Sorry I'm not the best at the topic
Also are there organisms that aren't asexual, female, or male?

[Stegotyranno420]

Oh, thanks for clarifying ? @Stolpergeist
But i meant like i already know about as*xual, I was asking if there was anything that was not asexual, nonsexual, male, or female, like another s*x. Like if we found aliens, would they be a different s*x, I mean they evolved independently from earth animals, so we can't expect them be the exact thing(just like we cant expect them to have bones, have arms, have eys, etc)

[Halichoeres]

Sex is a biological phenomenon; gender is a sociological and cultural phenomenon. They are not synonyms, even though many people who should know better use them as such.

The terms male and female are just conventions, maleness and femaleness aren't homologous across taxa. Biologists simply use 'male' to refer to the sex with the smaller gamete, and 'female' to refer to the sex with the larger gamete. By the same convention, we call the smaller gamete sperm, and the larger gamete egg. Again, these are not homologous across taxa. The sperm of a pine tree has no evolutionary relationship to the sperm of a frog; it's just that both happen to be the smaller gamete and hence called sperm. If we met aliens with unequal sized gametes, we would surely apply the same convention, even though they would just as surely have different names for everything.

There are organisms with equal sized gametes, which we call isogamous. The sexes there are usually referred to as mating types, and denoted "+" or "-", although sometimes in yeasts "a" and "α" are used instead. Some unicellular organisms have 6 or 8 sexes or mating types.

There are also lots of things that are hermaphrodites (this is a perfectly good word to apply to some plants and animals, but you should never, ever apply it to a human). Many plants have both male and female parts (they produce both sperm and egg), and many kinds of snails also have both kinds of gametes and will either fertilize each other or fight each other to determine who fertilizes whom. They are called simultaneous hermaphrodites. Many fishes are sequential hermaphrodites, which means they can be both sexes, but at different times of their life. Clownfishes start male and can become female under the right circumstances. So for example, in Finding Nemo, when Nemo's mom died, Marlin should have just turned female. Most wrasses are the opposite--they start female, but a large member of a given group will atrophy its ovaries and start making sperm instead.

Finally, I suspect that you are thinking of sex as genetically determined. But it can be determined by other factors, like temperature (crocodiles, turtles), or what you land on as a larva (Bonellia worms), or your social environment (the fishes I just discussed).

[Dusty Wren]

@Halichoeres, that's really fascinating stuff; thanks for taking the time to type it out. The sheer variety of reproductive strategies on this planet is wild.

[indohyus]

To get back on topic a bit, ammonites are an interesting one in terms of identifying sex. Males are generally smaller and more ornate (for attracting mates), while females are larger (due to egg development) and more plain. Many were identified as separate species for how diverse they can be, until they were found to be the same.

[Stegotyranno420]

I see. Thanks for answering my questions

@indohyus interesting indeed. How can we tell they were the same tho?

[indohyus]

I see. Thanks for answering my questions

@indohyus interesting indeed. How can we tell they were the same tho?

Location, the shape of the whorl (the spiral) and the ribbing of the ammonite.

[HD-man]

There is a pattern among living dinos. "In most species...males are larger than females...[while in hypercarnivorous predator species, females] tend to be stronger, larger, and more dominant than males" ( https://books.google.com/books?id=hTTUBAAAQBAJ&pg=PA6&dq=%22birds,+males+are+larger%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwimtZO-_u7pAhWXt54KHWCUCbgQ6AEwAHoECAUQAg#v=onepage&q=%22birds%2C%20males%20are%20larger%22&f=false ). I wouldn't be surprised if the same pattern applied to extinct dinos, especially given what we know about coelophysoids & T.rex (See the following quotes).

Quoted from Ricqlès 1992:

It is also worthy to note that Syntarsus seems to be a dimorphic species with both gracile and massive specimens at the same individual age (as assessed by skeletochronol- ogy). Since only the robust individuals show large perimedullar erosion cavities in their long bones, they are tentatively interpreted as females, as calcium is removed from the bones to allow for eggshell calcification (Chinsamy 1988, 1990).

Quoted from Prondvai 2016:

Identifying sexually dimorphic morphological characteristics in taxa where MB‐like tissues have been reported, as is the case in Confuciusornis (Chinsamy et al., 2013) may help testing the female‐specific presence of these tissues. For instance, it is generally accepted that gracile and more robust forms of Tyrannosaurus are males and females, respectively (Carpenter, 1990; Larson, 1994). Tyrannosaurus specimen MOR 1125 has been categorized as a robust form based on its femoral proportions (Larson, 2008), which is in line with the presence of MB in the same element (Schweitzer et al., 2005, 2016).

[Stegotyranno420]

I'm pretty sure it's now ruled as geographical distinction

[Halichoeres]

Halichoeres, that's really fascinating stuff; thanks for taking the time to type it out. The sheer variety of reproductive strategies on this planet is wild.

I just taught my intro bio students about mating systems, so I was primed   The variety really is staggering!


Chaohusaurus has been tentatively sexed using a set of specimens that included a gravid female: https://www.nature.com/articles/s41598-018-33302-4

[Newt]

@Halichoeres - have you come across "kleptogamy"? The Laurentian region of North America is infested with an all-female polyploid hybrid swarm of Ambystoma salamanders involving genotypes from five parent species. Apparently, the hybrids share a unique mtDNA profile distinct from any of the parents. This has lead to the idea that there was once a sixth Ambystoma species whose females preferentially mated with non-conspecific males, ultimately disappearing as an independent entity and surviving only as a mitochondrial relic in the hybrid swarm.


I have no idea if this hypothesis is still considered valid, but it was much discussed in my long-ago college days.


@Stegotyranno420 - not in coelophysids. Robust and gracile morphs are known for C. baurii from the Ghost Ranch Quarry sample, which were animals all living in the same time and place. Of course, it's also possible that two closely related species were flocking together, as is seen with many birds today, but the fact that the same two (not three or four or ten) morphs also show up in C. rhodesiensis, millions of years later and on another continent, makes it seem more likely to be dimorphism.


Sexual dimorphism is pretty well established in phytosaurs, with many species having a larger, more robust morph with a crested snout and a smaller, more gracile morph with a crestless snout. The larger morph is generally assumed to be the male, but this is strictly by analogy with extant species and has not been independently confirmed by, for example, a fossil of a gravid individual of one of the morphs.

[Stegotyranno420]

@Newt well im screwed. I made a few stories and art of bulky male coelophysids and gracile females
How about "dilophosaurids"(not the actual term, more like a wastebasket) like crylophosaurus, dilophosaurus, lilliensternus, y'know, all them early-theropods

[TethysaurusUK]

The term is "Sexual dimorphism".

I understand that. I just prefer using dimorphism over S**ual Dimorphism. Pretty sure its interchangeable.
Anyways, moving on, are there any other examples?

That leaves a bit of a problem then: if I was to dilute it down to dimorphism then that terms context expands to sexual dimorphism, intraspecific dimorphism, ontogenetic dimorphism, population dimorphism, chronostratigraphic dimorphism, etc., etc.. We have to be specific in order to distinguish.

[HD-man]

I'm pretty sure it's now ruled as geographical distinction

@Stegotyranno420 - not in coelophysids.

Or in T.rex. From what I remember, Larson 2008 covers geographic/stratigraphic distribution on pages 106-114 & concludes, "Neither geographic nor stratigraphic distribution can explain these differences."

[Halichoeres]

Halichoeres - have you come across "kleptogamy"? The Laurentian region of North America is infested with an all-female polyploid hybrid swarm of Ambystoma salamanders involving genotypes from five parent species. Apparently, the hybrids share a unique mtDNA profile distinct from any of the parents. This has lead to the idea that there was once a sixth Ambystoma species whose females preferentially mated with non-conspecific males, ultimately disappearing as an independent entity and surviving only as a mitochondrial relic in the hybrid swarm.


I have no idea if this hypothesis is still considered valid, but it was much discussed in my long-ago college days.

I was not familiar with the Ambystoma example! I'm familiar with kleptogamy in terms of 'sneaker males' in gobies and salmonids, and I'm familiar with all-female livebearer species that will still mate with males of other species but don't incorporate their sperm into the 'zygote,' which is instead a straightforward clone.

It takes all kinds!