Hey guys, another silly question…
Is it possible to know if therapsids have ears?
On 1/30/24 8:47 PM, jillery wrote:Though
On Sun, 28 Jan 2024 16:17:58 -0800, John Harshman
<john.harshman@gmail.com> wrote:
On 1/28/24 3:47 PM, trolidous wrote:
On 1/26/24 06:29, Sight Reader wrote:The meaning was clear from context in the OP. As for your last two
> Hey guys, another silly question…
>
> Is it possible to know if therapsids have ears?
Is the meaning of the word 'ear' knowable?
If not, then it may not be possible to know
if anyone or anything has 'ears'?
Does this bird have 'ears'? Who can really know?
https://en.wikipedia.org/wiki/Eurasian_eagle-owl
questions, yes, it does, and I can.
Interestingly, eared nightjars have ears, but so do all the other
nighjars. Eared grebes have ears, but so do all the other grebes.
not in the sense the OP meant.
The OP phrased its point poorly, failing to distinguish between "ear",
an organ that senses balance and atmospheric vibrations, and "external
ear" aka pinna, a mammalian invention that improves acoustic
directionality. Not all therapsids are mammals, and non-mammal
therapsids certainly had ears but probably not external ears. This
does not suggest all mammals have pinna.
Also, birds are not therapsids, and their mention doesn't inform the
OP.
But they're theropods, which sounds very similar to those who have ears.
On 1/31/24 7:23 AM, jillery wrote:
On Wed, 31 Jan 2024 01:57:40 -0800, trolidous <trolidous@go.com>
wrote:
On 1/30/24 21:53, John Harshman wrote:
On 1/30/24 8:47 PM, jillery wrote:Though
On Sun, 28 Jan 2024 16:17:58 -0800, John Harshman
<john.harshman@gmail.com> wrote:
On 1/28/24 3:47 PM, trolidous wrote:
On 1/26/24 06:29, Sight Reader wrote:The meaning was clear from context in the OP. As for your last two >>>>>> questions, yes, it does, and I can.
> Hey guys, another silly question…
>
> Is it possible to know if therapsids have ears?
Is the meaning of the word 'ear' knowable?
If not, then it may not be possible to know
if anyone or anything has 'ears'?
Does this bird have 'ears'? Who can really know?
https://en.wikipedia.org/wiki/Eurasian_eagle-owl
Interestingly, eared nightjars have ears, but so do all the other
nighjars. Eared grebes have ears, but so do all the other grebes.
not in the sense the OP meant.
The OP phrased its point poorly, failing to distinguish between "ear", >>>>> an organ that senses balance and atmospheric vibrations, and "external >>>>> ear" aka pinna, a mammalian invention that improves acoustic
directionality. Not all therapsids are mammals, and non-mammal
therapsids certainly had ears but probably not external ears. This >>>>> does not suggest all mammals have pinna.
Also, birds are not therapsids, and their mention doesn't inform the >>>>> OP.
But they're theropods, which sounds very similar to those who have
ears.
Would you admit that the word 'ear' might have subtly different
meanings in different parts of the thread?
That would make an earful.
Let's face it, ears are everywhere. The walls have ears, ears of corn, dogears, wood ears, rabbit ears, the Big Ear. It's downright eerie.
On 2/23/24 5:54 PM, John Harshman wrote:
Was this his very last post in this group? If so, no sign that he wasI didn't notice any big changes in Peter before he fell silent. He
at all ailing.
On 1/26/24 7:10 PM, Peter Nyikos wrote:
On Friday, January 26, 2024 at 12:20:45 PM UTC-5, Sight Reader wrote: >>>> On Friday, January 26, 2024 at 7:52:42 AM UTC-7, John Harshman wrote: >>>>> On 1/26/24 6:29 AM, Sight Reader wrote:
Hey guys, another silly question…
Is it possible to know if therapsids have ears? Most portrayals
give them these smooth, lumpy heads that look a bit like melted
lava lamps. However, once they decided it was OK to portray
Cynodonts with fur, the temptation to make them “look right” by >>>>>> adding ears seems overwhelming, but as a consequence the locations >>>>>> and shapes of the ears I’m seeing seem to be all over the place.
Well, of course living therapsids do. Or do they? Do monotremes have >>>>> pinnae (which is what you mean by "ears")? I don't recall seeing any, >>>>> though aquatic lifestyle in platypodes and spines in echidnas may
confuse the issue. Still, there's a suggestion that pinnae are at
least
a stem-therian invention.
John may be right here, Sight Reader. Even when I was a small boy, I
was aware that
frogs and snakes had no pinnae, and as I grew, one non-mammal after
another
was added to the list. For a while I thought some birds might have
some hidden by
feathers, but that too turned out to be wrong.
However, I still wonder about pterosaurs. In the olden days their
other features
were depicted as similar to those of bats, some of which have truly
enormous ears.
Even the great _Illustrated_Encyclopedia_of_Pterosaurs_, by Dr. Peter
Wellnhofer,
shows them as a drab gray throughout. Yet why would they be so if
they were diurnal?
On the other hand, might some of them have been nocturnal?
And if so, why not a use of echolocation, for which external ears
would have been an asset?
If cynodonts, dinocephalians, dicyondonts, gorgonopsians, etc etc
had ears, where would they be? Would they be near the jaw joint or >>>>>> just above it?
The eardrum is close to the jaw joint in therapsids, and there is a
very long discussion
about the relationship between the jaw and hearing in the transition
leading up to
mammals in Carroll's book on pages 394 - 395.
In summary: the jaw joint in early therapsids was formed by the tiny
quadrate and
articular. In mammals, these became bones of the middle ear while the
jaw joint passed
through a "double joint" stage followed by the migration of these
tiny bones into the
middle ear. The quadrate became the incus ("anvil") and the articular
became the malleus ("hammer").
There is a series of illustrations in Romer's _Vertebrate
Paleontology_ near the beginning
of the chapter on amphibians which traces the development of the
auditory region
from fish to humans. It is helpful to combine these very clear
illustrations with Carroll's account,
where the illustrations are harder to make out, and are confined to
the changes from
more advanced therapsids to mammals. During part of that time, the
eardrum (tympanum,
or tympanic membrane) apparently emerged to replace a "reflected
lamina", and became attached
to another bone, the angular, which became the tympanic bone in mammals. >>>
It's all complicated, and it took me so long to get the details
straight,
I didn't get to do nearly as many posts today as I would have liked.
Oh, well, Monday is another day.
Naturally, fleshy ears won’t fossilize, but if those ears had
muscles that could perk them in reaction to sound, might such
muscles leave some trace on the bone so you could at least locate
the ear correctly?
Hmmm… Firstly, thanks for introducing me to the word “pinnae”… so >>>> THAT’S what that is! Secondly, I thought, technically speaking, that >>>> “therapsid” was supposed to be a “grade”, meaning that, despite >>>> their descendents being all mammals still running around, they
nevertheless went extinct when the cynodonts and dicynodonts
disappeared somewhere in the Mesozoic.
On the thread about platypuses begun by Popping Mad, I had occasion
to talk about
the grade of non-mammalian therapsids, and even John Harshman is
familiar
with the grade of "nonavian dinosaurs." However, if his wish of
"Aves" being attached to
the crown group of birds is granted, he may have to settle for
"non-avialan dinosaurs" to be logical.
I never stopped to consider the loss of ears in aquatic mammals:
certainly dolphins and whales have no need for fleshy ears. However,
I think all mammals have to go through the evolutionary “choke
point” of the first few being the rodent-like descendents of
cynodonts. Now, if those little Mesozoic pests had ears, then I
think could comfidently say that pinnae are plesiomorphic (if I’m
using that word right?) for mammals, meaning that those aquatic guys
must have secondarily lost their ears.
What’s interesting is to wonder when these pinnae started to appear. >>>> Did the first cynodonts have them? Might fleshy ears have predated
the split of cynodonts from the other therapsids, meaning that
perhaps even dicynodonts, gorgonopsians or even dinocephalians might
have had them? Do pinnae leave any sort of trace on the underlying
bone, perhaps Sharpey’s fibers or something?
These are certainly interesting questions, but I'm as much in the dark
about the answers as John.
Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
University of South Carolina
https://people.math.sc.edu/nyikos
really was an interesting character. If something interested him that
he hadn't already formed an opinion of, he was still capable of thinking
and learning.
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