Open access article with Paul Sereno:
Spinosaurus is not an aquatic dinosaur
Abstract
A predominantly fish-eating diet was envisioned for the sail-backed
theropod dinosaur Spinosaurus aegyptiacus when its elongate jaws with subconical teeth were unearthed a century ago in Egypt. Recent
discovery of the high-spined tail of that skeleton, however, led to a
bolder conjecture that S. aegyptiacus was the first fully aquatic
dinosaur.
The āaquatic hypothesisā posits that S. aegyptiacus was a
slow quadruped on land but a capable pursuit predator in coastal
waters, powered by an expanded tail. We test these functional claims
with skeletal and flesh models of S. aegyptiacus. We assembled a
CT-based skeletal reconstruction based on the fossils, to which we
added internal air and muscle to create a posable flesh model. That
model shows that on land S. aegyptiacus was bipedal and in deep water
was an unstable, slow-surface swimmer (<1 m/s) too buoyant to dive.
Living reptiles with similar spine-supported sails over trunk and tail
are used for display rather than aquatic propulsion, and nearly all
extant secondary swimmers have reduced limbs and fleshy tail flukes.
New fossils also show that Spinosaurus ranged far inland. Two stages
are clarified in the evolution of Spinosaurus, which is best
understood as a semiaquatic bipedal ambush piscivore that frequented
the margins of coastal and inland waterways. https://elifesciences.org/articles/80092
On Friday, December 16, 2022 at 12:05:46 PM UTC-5, Pandora wrote:
Open access article with Paul Sereno:
Pardon my asking: does "with" mean that you are one of the co-authors?
Or is it shorthand for "by Paul Sereno and co-authors"?
On Fri, 16 Dec 2022 18:31:00 -0800 (PST), Peter Nyikos
<peter2...@gmail.com> wrote:
On Friday, December 16, 2022 at 12:05:46 PM UTC-5, Pandora wrote:
Open access article with Paul Sereno:
Pardon my asking: does "with" mean that you are one of the co-authors?I thought I'd let you know a celebrity is throwing his weight into
Or is it shorthand for "by Paul Sereno and co-authors"?
this discussion, and it's not me. ;-)
Sereno's recognitions include People magazine's 50 Most Beautiful
People (1997), Esquire's 100 Best People in the World (1997). https://explorer-directory.nationalgeographic.org/paul-c-sereno
FINALLY made it to Christmas breakā¦. at last, time for another quick dip into my hobbies!legs!
Wow, so based on the reconstructions they have, it sounds like their Spinosaurus would be a bipedal dinosaur who carries its body nearly horizontally! Have there been any other bipeds like that? It seems crazy, all that weight on such relatively short
On 12/18/22 10:06 AM, Sight Reader wrote:short legs!
FINALLY made it to Christmas breakā¦. at last, time for another quick dip into my hobbies!
Wow, so based on the reconstructions they have, it sounds like their Spinosaurus would be a bipedal dinosaur who carries its body nearly horizontally! Have there been any other bipeds like that? It seems crazy, all that weight on such relatively
Just about any theropod, and notably many of the living ones?
Not sure about the rest, but the Sereno et al. paper did conclude thatPrecisely! What Iām trying to say is that turning gigantic dinosaur like that with tiny little legs directly under the center of gravity would be like trying to turn a gigantic 20-ton propeller by trying to grab the hub: the part closest to the center
the center of gravity of the beasty was at its hips.
On Sunday, December 18, 2022 at 7:46:48 PM UTC-7, John Harshman wrote:short legs!
On 12/18/22 10:06 AM, Sight Reader wrote:
FINALLY made it to Christmas breakā¦. at last, time for another quick dip into my hobbies!
Wow, so based on the reconstructions they have, it sounds like their Spinosaurus would be a bipedal dinosaur who carries its body nearly horizontally! Have there been any other bipeds like that? It seems crazy, all that weight on such relatively
With legs so short, itās hard for me to picture how theyād get enough horizontal ātorqueā (if thatās the right word?) needed to change the dinosaurās direction: Iād think movements of that massive head or tail would generate way more torqueJust about any theropod, and notably many of the living ones?
Yay, thanks for the reply! Sorry about that stupid āhorizontalā part; thatās a pretty embarrassing misstatement (turns very red).
Anyway, what Iām utterly failing to comprehend is the āshort legsā part. Even compared to Suchomimus, the hind legs of Spinosaurus are SO short! For a dinosaur that massive, wouldnāt it be difficult to turn or maneuver anywhere but forward?
Apologies again if these questions are astoundingly stupid; once again, Iām new at this.
On Monday, December 19, 2022 at 7:35:38 AM UTC-7, John Harshman wrote:center of gravity is the hardest to turn because you have no leverage or āmoment armā, like the long handle on a wrench.
Not sure about the rest, but the Sereno et al. paper did conclude thatPrecisely! What Iām trying to say is that turning gigantic dinosaur like that with tiny little legs directly under the center of gravity would be like trying to turn a gigantic 20-ton propeller by trying to grab the hub: the part closest to the
the center of gravity of the beasty was at its hips.
On Monday, December 19, 2022 at 7:35:38 AM UTC-7, John Harshman wrote:
center of gravity is the hardest to turn because you have no leverage or āmoment armā, like the long handle on a wrench.Not sure about the rest, but the Sereno et al. paper did conclude that
the center of gravity of the beasty was at its hips.
Precisely! What Iām trying to say is that turning gigantic dinosaur like that with tiny little legs directly under the center of gravity would be like trying to turn a gigantic 20-ton propeller by trying to grab the hub: the part closest to the
Welcome back, Sight Reader! I'm glad you are over your final exams. Did you spend some of your Thanksgiving breakcenter of gravity is the hardest to turn because you have no leverage or āmoment armā, like the long handle on a wrench.
trying to get caught up?
On Monday, December 19, 2022 at 9:49:09 AM UTC-5, thesigh...@gmail.com wrote:
On Monday, December 19, 2022 at 7:35:38 AM UTC-7, John Harshman wrote:
A little tip: don't delete so much. It's hard to know what "the rest" is when you don't leave
any of your own words in from the earlier post. [Yes, ]we all know how to scroll up, but
that interrupts the rest of the thought.
Not sure about the rest, but the Sereno et al. paper did conclude that
the center of gravity of the beasty was at its hips.
Precisely! What Iām trying to say is that turning gigantic dinosaur like that with tiny little legs directly under the center of gravity would be like trying to turn a gigantic 20-ton propeller by trying to grab the hub: the part closest to the
Wait--why do you talk about the tiny little legs being directly under the center of gravity
when they aren't the ones connected to the hips?
As for "hardest to turn": I get the impression from the abominably unhelpful Wikipedia that the gluteus maximus is responsible for raising
the front of the body, and it has plenty of leverage from the attachment at the bottom of the hip.
I do believe that the non-theropod Plateosaurus was a biped that also got down on all fours a lot. Another
non-theropod, Stegosaurus looks like a quadruped that might often have reared up on its much bigger hind legs.
Thanks for the corrections, John. I have some comments below.short legs!
On Sunday, December 18, 2022 at 9:46:48 PM UTC-5, John Harshman wrote:
On 12/18/22 10:06 AM, Sight Reader wrote:
FINALLY made it to Christmas breakā¦. at last, time for another quick dip into my hobbies!
Wow, so based on the reconstructions they have, it sounds like their Spinosaurus would be a bipedal dinosaur who carries its body nearly horizontally! Have there been any other bipeds like that? It seems crazy, all that weight on such relatively
Just about any theropod, and notably many of the living ones?
Since there are no living theropods,
I take it "ones" refers to "bipeds", specifically birds.
Bipedal mammals, on the other hand, are all exceptions AFAIK.
This includes not only ourselves, but also indris, sifakas and avahis,
all of which are lemurs. I believe tarsiers are another exception.
On 12/18/22 10:06 AM, Sight Reader wrote:short legs!
FINALLY made it to Christmas breakā¦. at last, time for another quick dip into my hobbies!
Wow, so based on the reconstructions they have, it sounds like their Spinosaurus would be a bipedal dinosaur who carries its body nearly horizontally! Have there been any other bipeds like that? It seems crazy, all that weight on such relatively
Just about any theropod, and notably many of the living ones?
On 12/19/22 1:07 PM, Peter Nyikos wrote:short legs!
Thanks for the corrections, John. I have some comments below.
On Sunday, December 18, 2022 at 9:46:48 PM UTC-5, John Harshman wrote:
On 12/18/22 10:06 AM, Sight Reader wrote:
FINALLY made it to Christmas breakā¦. at last, time for another quick dip into my hobbies!
Wow, so based on the reconstructions they have, it sounds like their Spinosaurus would be a bipedal dinosaur who carries its body nearly horizontally! Have there been any other bipeds like that? It seems crazy, all that weight on such relatively
Just about any theropod, and notably many of the living ones?
Since there are no living theropods,
Have you learned nothing from me?
I take it "ones" refers to "bipeds", specifically birds.
Bipedal mammals, on the other hand, are all exceptions AFAIK.
This includes not only ourselves, but also indris, sifakas and avahis,
all of which are lemurs. I believe tarsiers are another exception.
What about kangaroos?
Check out the QANTAS logo.
On 12/19/22 10:55 AM, Peter Nyikos wrote:center of gravity is the hardest to turn because you have no leverage or āmoment armā, like the long handle on a wrench.
Welcome back, Sight Reader! I'm glad you are over your final exams. Did you spend some of your Thanksgiving break
trying to get caught up?
On Monday, December 19, 2022 at 9:49:09 AM UTC-5, thesigh...@gmail.com wrote:
On Monday, December 19, 2022 at 7:35:38 AM UTC-7, John Harshman wrote:
A little tip: don't delete so much. It's hard to know what "the rest" is when you don't leave
any of your own words in from the earlier post. [Yes, ]we all know how to scroll up, but
that interrupts the rest of the thought.
Not sure about the rest, but the Sereno et al. paper did conclude that >>> the center of gravity of the beasty was at its hips.
Precisely! What Iām trying to say is that turning gigantic dinosaur like that with tiny little legs directly under the center of gravity would be like trying to turn a gigantic 20-ton propeller by trying to grab the hub: the part closest to the
Wait--why do you talk about the tiny little legs being directly under the center of gravityI believe the ones connected to the hips are in fact what he's talking about.
when they aren't the ones connected to the hips?
As for "hardest to turn": I get the impression from the abominably unhelpful Wikipedia that the gluteus maximus is responsible for raisingAnd he's talking about turning left and right.
the front of the body, and it has plenty of leverage from the attachment at the bottom of the hip.
I do believe that the non-theropod Plateosaurus was a biped that also got down on all fours a lot. AnotherAnd note, both of the descended from obligate bipeds. Whether any
non-theropod, Stegosaurus looks like a quadruped that might often have reared up on its much bigger hind legs.
spinosaurs ever got down on all fours is an open question.
On 12/19/22 10:55 AM, Peter Nyikos wrote:center of gravity is the hardest to turn because you have no leverage or āmoment armā, like the long handle on a wrench.
Welcome back, Sight Reader! I'm glad you are over your final exams. Did you spend some of your Thanksgiving break
trying to get caught up?
On Monday, December 19, 2022 at 9:49:09 AM UTC-5, thesigh...@gmail.com wrote:
On Monday, December 19, 2022 at 7:35:38 AM UTC-7, John Harshman wrote:
A little tip: don't delete so much. It's hard to know what "the rest" is when you don't leave
any of your own words in from the earlier post. [Yes, ]we all know how to scroll up, but
that interrupts the rest of the thought.
Not sure about the rest, but the Sereno et al. paper did conclude that >>> the center of gravity of the beasty was at its hips.
Precisely! What Iām trying to say is that turning gigantic dinosaur like that with tiny little legs directly under the center of gravity would be like trying to turn a gigantic 20-ton propeller by trying to grab the hub: the part closest to the
Wait--why do you talk about the tiny little legs being directly under the center of gravityI believe the ones connected to the hips are in fact what he's talking about.
when they aren't the ones connected to the hips?
As for "hardest to turn": I get the impression from the abominably unhelpful Wikipedia that the gluteus maximus is responsible for raisingAnd he's talking about turning left and right.
the front of the body, and it has plenty of leverage from the attachment at the bottom of the hip.
I do believe that the non-theropod Plateosaurus was a biped that also got down on all fours a lot. AnotherAnd note, both of the descended from obligate bipeds. Whether any
non-theropod, Stegosaurus looks like a quadruped that might often have reared up on its much bigger hind legs.
spinosaurs ever got down on all fours is an open question.
On Monday, December 19, 2022 at 4:12:36 PM UTC-5, John Harshman wrote:short legs!
On 12/19/22 1:07 PM, Peter Nyikos wrote:
Thanks for the corrections, John. I have some comments below.
On Sunday, December 18, 2022 at 9:46:48 PM UTC-5, John Harshman wrote:
On 12/18/22 10:06 AM, Sight Reader wrote:
FINALLY made it to Christmas breakā¦. at last, time for another quick dip into my hobbies!
Wow, so based on the reconstructions they have, it sounds like their Spinosaurus would be a bipedal dinosaur who carries its body nearly horizontally! Have there been any other bipeds like that? It seems crazy, all that weight on such relatively
Just about any theropod, and notably many of the living ones?
Since there are no living theropods,
Have you learned nothing from me?
I'm sorry, but I refuse to adopt the jargon "birds are dinosaurs."
They are *descended from* what you call "non-avian dinosaurs"
and I call "dinosaurs."
How would you like it if I kept calling you "a unicellular eukaryote,"
just because you are descended from them?
I take it "ones" refers to "bipeds", specifically birds.
Bipedal mammals, on the other hand, are all exceptions AFAIK.
This includes not only ourselves, but also indris, sifakas and avahis,
all of which are lemurs. I believe tarsiers are another exception.
What about kangaroos?
I was thinking in terms of "vertical bipeds," and kangaroos hold
themselves at an angle, which would be closer to horizontal
if it were not for the big fleshy tails. But thanks for the reminder.
Getting back to paleontology: I've often wondered why
the pantodont *Barylambda* is shown with a long thick tail like a kangaroo. They are the only non-aquatic mammals I can think of with such big thick tails in proportion to their bodies. [Well, OK, wallabies and other "miniature kangaroos."]
Check out the QANTAS logo.
Have you learned nothing *about* me? I've been fascinated by
marsupials (also monotremes) since before the age of 12.
As if that weren't enough, my wife grew up in Australia,
and we were married there. We even saw a dead wallaby on the road
on our honeymoon, and my wife stopped the car to get it off the road.
On 12/19/22 1:53 PM, Peter Nyikos wrote:short legs!
On Monday, December 19, 2022 at 4:12:36 PM UTC-5, John Harshman wrote:
On 12/19/22 1:07 PM, Peter Nyikos wrote:
Thanks for the corrections, John. I have some comments below.
On Sunday, December 18, 2022 at 9:46:48 PM UTC-5, John Harshman wrote: >>>> On 12/18/22 10:06 AM, Sight Reader wrote:
FINALLY made it to Christmas breakā¦. at last, time for another quick dip into my hobbies!
Wow, so based on the reconstructions they have, it sounds like their Spinosaurus would be a bipedal dinosaur who carries its body nearly horizontally! Have there been any other bipeds like that? It seems crazy, all that weight on such relatively
Just about any theropod, and notably many of the living ones?
Since there are no living theropods,
Have you learned nothing from me?
I'm sorry, but I refuse to adopt the jargon "birds are dinosaurs."
They are *descended from* what you call "non-avian dinosaurs"
and I call "dinosaurs."
How would you like it if I kept calling you "a unicellular eukaryote," just because you are descended from them?Wrong comparison. How would you like if I kept calling you a mammal,
just because you are descended from them? In your comparison, it's "unicellular" that's doing the work. I presume you're fine with being a eukaryote. But of course "unicellular eukaryote" isn't a group.
I take it "ones" refers to "bipeds", specifically birds.
Bipedal mammals, on the other hand, are all exceptions AFAIK.
This includes not only ourselves, but also indris, sifakas and avahis, >>> all of which are lemurs. I believe tarsiers are another exception.
What about kangaroos?
I was thinking in terms of "vertical bipeds," and kangaroos hold themselves at an angle, which would be closer to horizontalNo, it's horizontal precisely because of the big fleshy tail. When
if it were not for the big fleshy tails. But thanks for the reminder.
moving fast they are indeed horizontal, balanced over the hind legs.
Like a theropod.
Getting back to paleontology: I've often wondered why
the pantodont *Barylambda* is shown with a long thick tail like a kangaroo.
They are the only non-aquatic mammals I can think of with such big thick tails in proportion to their bodies. [Well, OK, wallabies and other "miniature kangaroos."]
Check out the QANTAS logo.
Have you learned nothing *about* me? I've been fascinated bySo you have no excuse for forgetting about them.
marsupials (also monotremes) since before the age of 12.
As if that weren't enough, my wife grew up in Australia,
and we were married there. We even saw a dead wallaby on the road
on our honeymoon, and my wife stopped the car to get it off the road.
Open access article with Paul Sereno:
Spinosaurus is not an aquatic dinosaur
On Monday, December 19, 2022 at 9:26:43 PM UTC-8, John Harshman wrote:short legs!
On 12/19/22 1:53 PM, Peter Nyikos wrote:
On Monday, December 19, 2022 at 4:12:36 PM UTC-5, John Harshman wrote:
On 12/19/22 1:07 PM, Peter Nyikos wrote:
Thanks for the corrections, John. I have some comments below.
On Sunday, December 18, 2022 at 9:46:48 PM UTC-5, John Harshman wrote: >> >>>> On 12/18/22 10:06 AM, Sight Reader wrote:
FINALLY made it to Christmas breakā¦. at last, time for another quick dip into my hobbies!
Wow, so based on the reconstructions they have, it sounds like their Spinosaurus would be a bipedal dinosaur who carries its body nearly horizontally! Have there been any other bipeds like that? It seems crazy, all that weight on such relatively
Wrong comparison. How would you like if I kept calling you a mammal,
Just about any theropod, and notably many of the living ones?
Since there are no living theropods,
Have you learned nothing from me?
I'm sorry, but I refuse to adopt the jargon "birds are dinosaurs."
They are *descended from* what you call "non-avian dinosaurs"
and I call "dinosaurs."
How would you like it if I kept calling you "a unicellular eukaryote,"
just because you are descended from them?
just because you are descended from them? In your comparison, it's
"unicellular" that's doing the work. I presume you're fine with being a
eukaryote. But of course "unicellular eukaryote" isn't a group.
No, it's horizontal precisely because of the big fleshy tail. WhenI take it "ones" refers to "bipeds", specifically birds.
Bipedal mammals, on the other hand, are all exceptions AFAIK.
This includes not only ourselves, but also indris, sifakas and avahis, >> >>> all of which are lemurs. I believe tarsiers are another exception.
What about kangaroos?
I was thinking in terms of "vertical bipeds," and kangaroos hold
themselves at an angle, which would be closer to horizontal
if it were not for the big fleshy tails. But thanks for the reminder.
moving fast they are indeed horizontal, balanced over the hind legs.
Like a theropod.
Getting back to paleontology: I've often wondered whySo you have no excuse for forgetting about them.
the pantodont *Barylambda* is shown with a long thick tail like a kangaroo.
They are the only non-aquatic mammals I can think of with such big thick >> > tails in proportion to their bodies. [Well, OK, wallabies and other "miniature kangaroos."]
Check out the QANTAS logo.
Have you learned nothing *about* me? I've been fascinated by
marsupials (also monotremes) since before the age of 12.
As if that weren't enough, my wife grew up in Australia,
and we were married there. We even saw a dead wallaby on the road
on our honeymoon, and my wife stopped the car to get it off the road.
Credit where credit is due (at least a little credit). Peter's learned at least
two things since he was twelve. He used to bulldog for Feduccia the way he >does now for Behe. Additionally, I think he accepts hippos as the sister group to
whales. Gradual evolution of his worldview; not saltation.
On Mon, 19 Dec 2022 21:47:59 -0800 (PST), erik simpsonrelatively short legs!
<eastsi...@gmail.com> wrote:
On Monday, December 19, 2022 at 9:26:43 PM UTC-8, John Harshman wrote:
On 12/19/22 1:53 PM, Peter Nyikos wrote:
On Monday, December 19, 2022 at 4:12:36 PM UTC-5, John Harshman wrote: >> >> On 12/19/22 1:07 PM, Peter Nyikos wrote:
Thanks for the corrections, John. I have some comments below.
On Sunday, December 18, 2022 at 9:46:48 PM UTC-5, John Harshman wrote:
On 12/18/22 10:06 AM, Sight Reader wrote:
FINALLY made it to Christmas breakā¦. at last, time for another quick dip into my hobbies!
Wow, so based on the reconstructions they have, it sounds like their Spinosaurus would be a bipedal dinosaur who carries its body nearly horizontally! Have there been any other bipeds like that? It seems crazy, all that weight on such
Wrong comparison. How would you like if I kept calling you a mammal,
Just about any theropod, and notably many of the living ones?
Since there are no living theropods,
Have you learned nothing from me?
I'm sorry, but I refuse to adopt the jargon "birds are dinosaurs."
They are *descended from* what you call "non-avian dinosaurs"
and I call "dinosaurs."
How would you like it if I kept calling you "a unicellular eukaryote," >> > just because you are descended from them?
just because you are descended from them? In your comparison, it's
"unicellular" that's doing the work. I presume you're fine with being a >> eukaryote. But of course "unicellular eukaryote" isn't a group.
moving fast they are indeed horizontal, balanced over the hind legs.I take it "ones" refers to "bipeds", specifically birds.
Bipedal mammals, on the other hand, are all exceptions AFAIK.
This includes not only ourselves, but also indris, sifakas and avahis,
all of which are lemurs. I believe tarsiers are another exception.
What about kangaroos?
I was thinking in terms of "vertical bipeds," and kangaroos hold
themselves at an angle, which would be closer to horizontal
if it were not for the big fleshy tails. But thanks for the reminder. >> No, it's horizontal precisely because of the big fleshy tail. When
Like a theropod.
Getting back to paleontology: I've often wondered why
the pantodont *Barylambda* is shown with a long thick tail like a kangaroo.
They are the only non-aquatic mammals I can think of with such big thick
tails in proportion to their bodies. [Well, OK, wallabies and other "miniature kangaroos."]
Check out the QANTAS logo.
Have you learned nothing *about* me? I've been fascinated by
marsupials (also monotremes) since before the age of 12.
As if that weren't enough, my wife grew up in Australia,
and we were married there. We even saw a dead wallaby on the road
on our honeymoon, and my wife stopped the car to get it off the road. >> So you have no excuse for forgetting about them.
Credit where credit is due (at least a little credit). Peter's learned at leastBefore giving credit where applicants are likely to default, you might
two things since he was twelve. He used to bulldog for Feduccia the way he >does now for Behe. Additionally, I think he accepts hippos as the sister group to
whales. Gradual evolution of his worldview; not saltation.
want to know what they mean by "gradual" more precisely than "not saltation".
On 12/19/22 2:23 PM, Sight Reader wrote:mouth to change feetā¦
Hey guys, thanks a ton for the feedback! Sorry about the snippingā¦ I didnāt want to flood you guys with excess information and didnāt realize that snipping make things inconvenient (feeling embarrassed yet AGAIN). Apparently I only open my
center of gravity (presumably over her hip): only her neck and head would be farther away from her center of gravity than where her foot is planted, but with such long legs, she can easily rear up and even move that mass closer to her center of mass.Anyways, regarding why I have concerns about this reconstruction of Spinosaurus but not about other theropods, Iām mostly referring to the ratio of stride length to where most of the body mass is.
Iāll give this my best shot. Letās consider, for example, your average T-rex. Just from eyeballing it, Iād say her front foot would land roughly under her neck. Note that this means that most of her mass would be between that front foot and her
still remains a LOT of mass outside of where that foot lands, including those big arms, the thick neck, and her even bigger head. Furthermore, she has very little clearance off the ground, so she canāt rear up quasi-erect to come about - she has toLetās now look at their reconstruction of Spinosaurus. If she puts her foot forward, Iām not even sure her foot makes it to her arms, which means that there is not nearly as much of her mass between her plant foot and her center of gravity: there
to be getting replaced by the little-leg version, especially those that show her swimming. I have no idea which is right.I would finally note that older reconstructions of Spinosaurus - notably the one in Jurassic Park III but there are still quite a few others sitting around - all give her much longer legs than theyāre reconstructed. However, these portrayals seem
center of gravity is the hardest to turn because you have no leverage or āmoment armā, like the long handle on a wrench.Sorry that was so long! I tried my bestā¦
On Monday, December 19, 2022 at 12:26:19 PM UTC-7, John Harshman wrote:
On 12/19/22 10:55 AM, Peter Nyikos wrote:
Welcome back, Sight Reader! I'm glad you are over your final exams. Did you spend some of your Thanksgiving break
trying to get caught up?
On Monday, December 19, 2022 at 9:49:09 AM UTC-5, thesigh...@gmail.com wrote:
On Monday, December 19, 2022 at 7:35:38 AM UTC-7, John Harshman wrote: >>>A little tip: don't delete so much. It's hard to know what "the rest" is when you don't leave
any of your own words in from the earlier post. [Yes, ]we all know how to scroll up, but
that interrupts the rest of the thought.
Not sure about the rest, but the Sereno et al. paper did conclude that >>>>> the center of gravity of the beasty was at its hips.
Precisely! What Iām trying to say is that turning gigantic dinosaur like that with tiny little legs directly under the center of gravity would be like trying to turn a gigantic 20-ton propeller by trying to grab the hub: the part closest to the
Ćpinosaurus is reconstructed with short legs because that's what theI believe the ones connected to the hips are in fact what he's talking
Wait--why do you talk about the tiny little legs being directly under the center of gravity
when they aren't the ones connected to the hips?
about.
As for "hardest to turn": I get the impression from the abominably unhelpful Wikipedia that the gluteus maximus is responsible for raisingAnd he's talking about turning left and right.
the front of the body, and it has plenty of leverage from the attachment at the bottom of the hip.
I do believe that the non-theropod Plateosaurus was a biped that also got down on all fours a lot. AnotherAnd note, both of the descended from obligate bipeds. Whether any
non-theropod, Stegosaurus looks like a quadruped that might often have reared up on its much bigger hind legs.
spinosaurs ever got down on all fours is an open question.
fossil material looks like. I don't see a way out of that. I would
propose that their feeding strategy didn't require them to turn their
torsos very fast. Perhaps they only lunged straight forward, and any corection of direction was done with the neck only.
On Tuesday, December 20, 2022 at 6:52:20 AM UTC-8, 69jp...@gmail.com wrote:relatively short legs!
On Mon, 19 Dec 2022 21:47:59 -0800 (PST), erik simpson
<eastsi...@gmail.com> wrote:
On Monday, December 19, 2022 at 9:26:43 PM UTC-8, John Harshman wrote:
On 12/19/22 1:53 PM, Peter Nyikos wrote:
On Monday, December 19, 2022 at 4:12:36 PM UTC-5, John Harshman wrote: >> >> >> On 12/19/22 1:07 PM, Peter Nyikos wrote:
Thanks for the corrections, John. I have some comments below.
On Sunday, December 18, 2022 at 9:46:48 PM UTC-5, John Harshman wrote:
On 12/18/22 10:06 AM, Sight Reader wrote:
FINALLY made it to Christmas breakā¦. at last, time for another quick dip into my hobbies!
Wow, so based on the reconstructions they have, it sounds like their Spinosaurus would be a bipedal dinosaur who carries its body nearly horizontally! Have there been any other bipeds like that? It seems crazy, all that weight on such
Before giving credit where applicants are likely to default, you mightWrong comparison. How would you like if I kept calling you a mammal,
Just about any theropod, and notably many of the living ones?
Since there are no living theropods,
Have you learned nothing from me?
I'm sorry, but I refuse to adopt the jargon "birds are dinosaurs."
They are *descended from* what you call "non-avian dinosaurs"
and I call "dinosaurs."
How would you like it if I kept calling you "a unicellular eukaryote," >> >> > just because you are descended from them?
just because you are descended from them? In your comparison, it's
"unicellular" that's doing the work. I presume you're fine with being a >> >> eukaryote. But of course "unicellular eukaryote" isn't a group.
moving fast they are indeed horizontal, balanced over the hind legs.I take it "ones" refers to "bipeds", specifically birds.What about kangaroos?
Bipedal mammals, on the other hand, are all exceptions AFAIK.
This includes not only ourselves, but also indris, sifakas and avahis,
all of which are lemurs. I believe tarsiers are another exception. >> >> >
I was thinking in terms of "vertical bipeds," and kangaroos hold
themselves at an angle, which would be closer to horizontal
if it were not for the big fleshy tails. But thanks for the reminder. >> >> No, it's horizontal precisely because of the big fleshy tail. When
Like a theropod.
Getting back to paleontology: I've often wondered why
the pantodont *Barylambda* is shown with a long thick tail like a kangaroo.
They are the only non-aquatic mammals I can think of with such big thick
tails in proportion to their bodies. [Well, OK, wallabies and other "miniature kangaroos."]
Check out the QANTAS logo.
Have you learned nothing *about* me? I've been fascinated by
marsupials (also monotremes) since before the age of 12.
As if that weren't enough, my wife grew up in Australia,
and we were married there. We even saw a dead wallaby on the road
on our honeymoon, and my wife stopped the car to get it off the road. >> >> So you have no excuse for forgetting about them.
Credit where credit is due (at least a little credit). Peter's learned at least
two things since he was twelve. He used to bulldog for Feduccia the way he >> >does now for Behe. Additionally, I think he accepts hippos as the sister group to
whales. Gradual evolution of his worldview; not saltation.
want to know what they mean by "gradual" more precisely than "not
saltation".
My remarks here don't require or deserve precision or even serious attention. >The words are mine, not Peter's. They simply reflect my amusement at Peter's >reluctance to accept changes to what he learned in his youth.
On Monday, December 19, 2022 at 10:33:54 PM UTC-7, John Harshman wrote:I didnāt want to flood you guys with excess information and didnāt
On 12/19/22 2:23 PM, Sight Reader wrote:
Hey guys, thanks a ton for the feedback! Sorry about the snippingā¦
ratio of stride length to where most of the body mass is.
Anyways, regarding why I have concerns about this reconstruction of Spinosaurus but not about other theropods, Iām mostly referring to the
average T-rex. Just from eyeballing it, Iād say her front foot would
Iāll give this my best shot. Letās consider, for example, your
her foot forward, Iām not even sure her foot makes it to her arms, which means that there is not nearly as much of her mass between her plant
Letās now look at their reconstruction of Spinosaurus. If she puts
notably the one in Jurassic Park III but there are still quite a few
I would finally note that older reconstructions of Spinosaurus -
exams. Did you spend some of your Thanksgiving break
Sorry that was so long! I tried my bestā¦
On Monday, December 19, 2022 at 12:26:19 PM UTC-7, John Harshman wrote:
On 12/19/22 10:55 AM, Peter Nyikos wrote:
Welcome back, Sight Reader! I'm glad you are over your final
thesigh...@gmail.com wrote:trying to get caught up?
On Monday, December 19, 2022 at 9:49:09 AM UTC-5,
wrote:On Monday, December 19, 2022 at 7:35:38 AM UTC-7, John Harshman
rest" is when you don't leave
A little tip: don't delete so much. It's hard to know what "the
know how to scroll up, butany of your own words in from the earlier post. [Yes, ]we all
conclude thatthat interrupts the rest of the thought.
Not sure about the rest, but the Sereno et al. paper did
dinosaur like that with tiny little legs directly under the center ofthe center of gravity of the beasty was at its hips.
Precisely! What Iām trying to say is that turning gigantic
under the center of gravity
Wait--why do you talk about the tiny little legs being directly
abominably unhelpful Wikipedia that the gluteus maximus is responsiblewhen they aren't the ones connected to the hips?I believe the ones connected to the hips are in fact what he's talking
about.
As for "hardest to turn": I get the impression from the
attachment at the bottom of the hip.the front of the body, and it has plenty of leverage from the
also got down on all fours a lot. AnotherAnd he's talking about turning left and right.
I do believe that the non-theropod Plateosaurus was a biped that
have reared up on its much bigger hind legs.non-theropod, Stegosaurus looks like a quadruped that might often
sized legs were based on incomplete remains? If thatās the case, IĆpinosaurus is reconstructed with short legs because that's what theAnd note, both of the descended from obligate bipeds. Whether any
spinosaurs ever got down on all fours is an open question.
fossil material looks like. I don't see a way out of that. I would
propose that their feeding strategy didn't require them to turn their
torsos very fast. Perhaps they only lunged straight forward, and any
corection of direction was done with the neck only.
I agree. I wonder if those earlier reconstructions with reasonably
Anyway, I was also wondering about the lunging forward hypothesis.Seems like not being able to turn very well would be a serious liability
Even if not completely aquatic, maybe hanging around in waterhabitats plays some sort of role in mitigating this vulnerability?
Iām starting to think thereās a certain Murphyās Law when it comes tointerpreting dinosaurs:
āWhatever interpretation makes the MOST sense is almost certainlygoing to be the one interpretation that can get definitely ruled outā¦ā
On 12/20/22 10:49 AM, Sight Reader wrote:
On Monday, December 19, 2022 at 10:33:54 PM UTC-7, John Harshman wrote:I didnāt want to flood you guys with excess information and didnāt realize that snipping make things inconvenient (feeling embarrassed yet AGAIN). Apparently I only open my mouth to change feetā¦
On 12/19/22 2:23 PM, Sight Reader wrote:
Hey guys, thanks a ton for the feedback! Sorry about the snippingā¦
land roughly under her neck. Note that this means that most of her mass would be between that front foot and her center of gravity (presumably
Anyways, regarding why I have concerns about this reconstruction of Spinosaurus but not about other theropods, Iām mostly referring to the ratio of stride length to where most of the body mass is.
Iāll give this my best shot. Letās consider, for example, your average T-rex. Just from eyeballing it, Iād say her front foot would
over her hip): only her neck and head would be farther away from her
center of gravity than where her foot is planted, but with such long
legs, she can easily rear up and even move that mass closer to her
center of mass. Since her stride length is longer than most of her mass,
she could push off of that foot, and the location her foot is planted
will have a reasonably long āmoment armā that can amplify the turning force on her center of mass. This would be more like pushing at the END
of the 20-ton propeller rather than trying to twist it at its hub: you donāt need nearly as much strength to get it rotating. Now to be clear, Iām not entirely sure how ANY of these theropods turned since their hips donāt seem to let them sprawl their legs out sideways to ācutā like we can: I would guess dinosaurs would require a certain level of ābankingā (leaning left or right into a turn) before coming about, but that should
be easy enough given sufficiently long legs and I think there are plenty
of animals that do that.
her foot forward, Iām not even sure her foot makes it to her arms, which means that there is not nearly as much of her mass between her plant
Letās now look at their reconstruction of Spinosaurus. If she puts
foot and her center of gravity: there still remains a LOT of mass
outside of where that foot lands, including those big arms, the thick
neck, and her even bigger head. Furthermore, she has very little
clearance off the ground, so she canāt rear up quasi-erect to come about
- she has to hold herself horizontal to avoid bottoming out, thus
keeping a significant portion of her mass outside of her stride length
(all of this could be SO EASILY described in about 10 words if only I
could post a pictureā¦ GAH!) Anyways, this is the problem of trying to
turn that 20-ton propeller by trying to twist it at its hub - without
being able to leverage further out to the āpropellerā, I just canāt see
how sheās going to maneuver. Now, if she was something of a quadruped,
she could plant her arms into the ground - which are much farther away
from the center of gravity and can thus exert torque without a
ridiculous amount of force, but apparently her arms have no weight
bearing function, so I donāt think she can do this unless she grabs a
tree or something. As far as my pet theory of ābankingā before turning goes, that too would be proportionally more difficult with her short clearance from the ground.
notably the one in Jurassic Park III but there are still quite a few
I would finally note that older reconstructions of Spinosaurus -
others sitting around - all give her much longer legs than theyāre reconstructed. However, these portrayals seem to be getting replaced by
the little-leg version, especially those that show her swimming. I have
no idea which is right.
exams. Did you spend some of your Thanksgiving break
Sorry that was so long! I tried my bestā¦
On Monday, December 19, 2022 at 12:26:19 PM UTC-7, John Harshman wrote: >>>> On 12/19/22 10:55 AM, Peter Nyikos wrote:
Welcome back, Sight Reader! I'm glad you are over your final
thesigh...@gmail.com wrote:trying to get caught up?
On Monday, December 19, 2022 at 9:49:09 AM UTC-5,
rest" is when you don't leaveOn Monday, December 19, 2022 at 7:35:38 AM UTC-7, John Harshman wrote:
A little tip: don't delete so much. It's hard to know what "the
know how to scroll up, butany of your own words in from the earlier post. [Yes, ]we all
conclude thatthat interrupts the rest of the thought.
Not sure about the rest, but the Sereno et al. paper did
dinosaur like that with tiny little legs directly under the center of gravity would be like trying to turn a gigantic 20-ton propeller bythe center of gravity of the beasty was at its hips.
Precisely! What Iām trying to say is that turning gigantic
trying to grab the hub: the part closest to the center of gravity is the hardest to turn because you have no leverage or āmoment armā, like the long handle on a wrench.
under the center of gravity
Wait--why do you talk about the tiny little legs being directly
abominably unhelpful Wikipedia that the gluteus maximus is responsiblewhen they aren't the ones connected to the hips?I believe the ones connected to the hips are in fact what he's talking >>>> about.
As for "hardest to turn": I get the impression from the
for raising
also got down on all fours a lot. Anotherthe front of the body, and it has plenty of leverage from the attachment at the bottom of the hip.And he's talking about turning left and right.
I do believe that the non-theropod Plateosaurus was a biped that
have reared up on its much bigger hind legs.non-theropod, Stegosaurus looks like a quadruped that might often
Ćpinosaurus is reconstructed with short legs because that's what theAnd note, both of the descended from obligate bipeds. Whether any
spinosaurs ever got down on all fours is an open question.
fossil material looks like. I don't see a way out of that. I would
propose that their feeding strategy didn't require them to turn their
torsos very fast. Perhaps they only lunged straight forward, and any
corection of direction was done with the neck only.
I agree. I wonder if those earlier reconstructions with reasonablysized legs were based on incomplete remains? If thatās the case, I
wonder which discovery revealed the true leg size.
The Wikipedia article on Spinosaurus will provide the references.
Anyway, I was also wondering about the lunging forward hypothesis.Seems like not being able to turn very well would be a serious liability
- someone is always getting around behind you (āSpino, Spino! Watch
your 6!ā) Trying to turn by simply redirecting your head would be frustrating because, instead of your body coming about, the rest of you simply rotates back the other way while your tiny feet are trying to
keep up (Hey, everyone knows what the girls say about guys with small feetā¦)
You assume here that some animal is a threat to an adult Spinosaurus.
That seems very unlikely. And of course the body doesn't have to come
about. If necessary, the tail could rotate a bit to counter the head movement. And this is about predation, not self-defense.
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