New small plesiosaur Unktaheela specta, and clarification of the genus Dolichorhynchops

[Faelrin]

Paper is paywalled:

https://www.sciencedirect.com/science/article/abs/pii/S0195667123003403?via%3Dihub

But there is this wonderful graphical abstract that should be helpful:



While Dolichorhynchops could certainly use a new figure of it, I'd certainly love to see this adorable little friend get a figure too. One last paleo gift for the year yes?

[Faelrin]

@DinoToyForum You're the plesiosaur expert around these parts, so what do you think of this new find?

[DinoToyForum]

@DinoToyForum You're the plesiosaur expert around these parts, so what do you think of this new find?

I haven't read the paper yet but it's interesting to see such a small species discovered in the Upper Cretaceous. The close relatives of true plesiosaurs include very small bodied species, for example, most pachypleurosaurs were small 30 cm long lizard-like creatures. I've always wondered why there are no similarly small-bodied plesiosaurs, I can't think of any reason why there couldn't be. This new discovery shows that small plesiosaurs did exist, even at the end of the Cretaceous Period. Still, not quite small enough to fit in the palm of your hand!

[VD231991]

The paper discussed in this thread also happens to erect the new genus Scalamagnus for Dolichorhynchops tropicensis while renaming Dolichorhychops bonneri (itself originally named as a species of Trinacromerum) as Martinectes. A number of cladistic analyses from a few years ago did not recover D. tropicensis as sister to D. osborni to the exclusion of other polycotylids, and the new paper confirms the generic distinctness of this taxon from osborni.

[Newt]

Scalamagnus would be a good name for an evil wizard...

Unktaheela looks to be about the size of a small porpoise based on that graphic. Cetaceans also don't occupy the smaller size ranges that other marine endotherms (seals, penguins) do, which I'd guess has to do with the thermoregulatory demands put on a newborn that can't leave the water. Has it been established whether plesiosaurs were endotherms?

If so, pachypleurosaurs may have either been ectotherms, nested on land, or been restricted to shallow waters that were at least seasonally warm. Same for some of the tiny early ichthyosaurs.

Just my unsupported speculation!

[DinoToyForum]

The paper discussed in this thread also happens to erect the new genus Scalamagnus for Dolichorhynchops tropicensis while renaming Dolichorhychops bonneri (itself originally named as a species of Trinacromerum) as Martinectes. A number of cladistic analyses from a few years ago did not recover D. tropicensis as sister to D. osborni to the exclusion of other polycotylids, and the new paper confirms the generic distinctness of this taxon from osborni.

This makes a lot of sense. I'll have to update my plesiosaur stratigraphy chart again to reflect these changes: https://i0.wp.com/plesiosauria.com/wp-content/uploads/stratigraphy_v4_2023_07.jpg

But even accounting for these changes, Dolichorhynchops retains the longest stratigraphic range, by far, of all valid plesiosaur genera. It extends over three stages, which suggests that a lot of referred D. osborni material may not really be. So, I'll have to check the full paper to see if the referred material is also revised.

[DinoToyForum]

For anyone interested, I updated my plesiosaur chart based on this and other recent studies: https://plesiosauria.com/wp-content/uploads/stratigraphy_v5_2024_01.jpg

[Newt]

For anyone interested, I updated my plesiosaur chart based on this and other recent studies: https://plesiosauria.com/wp-content/uploads/stratigraphy_v5_2024_01.jpg

Very interesting! The chart does make the point of D. osborni's unusually long temporal range more obvious. I don't think any of the mosasaur species it shared its environment with had such long ranges.

I'm also surprised by how early Plesiosaurus itself was. That's just my ignorance, of course, but I would not have guessed that the namebearer of the whole group was a basal form.

[DinoToyForum]

For anyone interested, I updated my plesiosaur chart based on this and other recent studies: https://plesiosauria.com/wp-content/uploads/stratigraphy_v5_2024_01.jpg

Very interesting! The chart does make the point of D. osborni's unusually long temporal range more obvious. I don't think any of the mosasaur species it shared its environment with had such long ranges.

I'm also surprised by how early Plesiosaurus itself was. That's just my ignorance, of course, but I would not have guessed that the namebearer of the whole group was a basal form.

Much of the long range of Dolichorhynchops osborni is made up of referred material, so if that gets reidentified (for example, as indeterminate ploycotylids) then the stratigraphic range could shrink down considerably. I need to read the new paper.

Yeah, the rocks at Lyme Regis where the first Plesiosaurus remains were found by Mary Anning are from the early part of the early Jurassic. Plesiosaurus was a waste basket taxon so its stratigraphic range used to stretch all the way through the Jurassic and Cretaceous! But today there is only one valid species of Plesiosaurus, hence the more constrained temporal range for the genus.

[microraptorgui]

For anyone interested, I updated my plesiosaur chart based on this and other recent studies: https://plesiosauria.com/wp-content/uploads/stratigraphy_v5_2024_01.jpg

Very interesting! The chart does make the point of D. osborni's unusually long temporal range more obvious. I don't think any of the mosasaur species it shared its environment with had such long ranges.

I'm also surprised by how early Plesiosaurus itself was. That's just my ignorance, of course, but I would not have guessed that the namebearer of the whole group was a basal form.

Much of the long range of Dolichorhynchops osborni is made up of referred material, so if that gets reidentified (for example, as indeterminate ploycotylids) then the stratigraphic range could shrink down considerably. I need to read the new paper.

Yeah, the rocks at Lyme Regis where the first Plesiosaurus remains were found by Mary Anning are from the early part of the early Jurassic. Plesiosaurus was a waste basket taxon so its stratigraphic range used to stretch all the way through the Jurassic and Cretaceous! But today there is only one valid species of Plesiosaurus, hence the more constrained temporal range for the genus.

Hi everyone, I'm the lead author of the Unktaheela paper. I've been part of the Dinosaur Toy Forum for years but don't post very often. But I'm happy to see this discussion about our research! Since some of you haven't been able to access the paper, I wanted to let you know that you can now read or download the entire thing for FREE before March 3 using this link!
https://authors.elsevier.com/a/1iQMaiVLDN60B

[microraptorgui]

Paper is paywalled:

https://www.sciencedirect.com/science/article/abs/pii/S0195667123003403?via%3Dihub

But there is this wonderful graphical abstract that should be helpful:



While Dolichorhynchops could certainly use a new figure of it, I'd certainly love to see this adorable little friend get a figure too. One last paleo gift for the year yes?

It would be so sweet to see a figure made of our new little polycotylid! I'd happily work with any company who wanted to produce an Unktaheela model. I actually sculpted a little reference maquette of my own as I was working on the life reconstruction.

[DinoToyForum]

For anyone interested, I updated my plesiosaur chart based on this and other recent studies: https://plesiosauria.com/wp-content/uploads/stratigraphy_v5_2024_01.jpg

Very interesting! The chart does make the point of D. osborni's unusually long temporal range more obvious. I don't think any of the mosasaur species it shared its environment with had such long ranges.

I'm also surprised by how early Plesiosaurus itself was. That's just my ignorance, of course, but I would not have guessed that the namebearer of the whole group was a basal form.

Much of the long range of Dolichorhynchops osborni is made up of referred material, so if that gets reidentified (for example, as indeterminate ploycotylids) then the stratigraphic range could shrink down considerably. I need to read the new paper.

Yeah, the rocks at Lyme Regis where the first Plesiosaurus remains were found by Mary Anning are from the early part of the early Jurassic. Plesiosaurus was a waste basket taxon so its stratigraphic range used to stretch all the way through the Jurassic and Cretaceous! But today there is only one valid species of Plesiosaurus, hence the more constrained temporal range for the genus.

Hi everyone, I'm the lead author of the Unktaheela paper. I've been part of the Dinosaur Toy Forum for years but don't post very often. But I'm happy to see this discussion about our research! Since some of you haven't been able to access the paper, I wanted to let you know that you can now read or download the entire thing for FREE before March 3 using this link!
https://authors.elsevier.com/a/1iQMaiVLDN60B

Ha, I literally just downloaded the paper before seeing your post here! Robin shared the link elsewhere.
I was just skimming through it, then googling images of the the black-legged seriema to see how the supraorbital process is expressed in life in that species.

Congratulations on the new paper, I'm looking forward to reading it fully, interesting discoveries!

[Faelrin]

@microraptorgui Thank you so much for sharing a way to read it. And I love that artwork you did too.

[microraptorgui]

For anyone interested, I updated my plesiosaur chart based on this and other recent studies: https://plesiosauria.com/wp-content/uploads/stratigraphy_v5_2024_01.jpg

Very interesting! The chart does make the point of D. osborni's unusually long temporal range more obvious. I don't think any of the mosasaur species it shared its environment with had such long ranges.

I'm also surprised by how early Plesiosaurus itself was. That's just my ignorance, of course, but I would not have guessed that the namebearer of the whole group was a basal form.

Much of the long range of Dolichorhynchops osborni is made up of referred material, so if that gets reidentified (for example, as indeterminate ploycotylids) then the stratigraphic range could shrink down considerably. I need to read the new paper.

Yeah, the rocks at Lyme Regis where the first Plesiosaurus remains were found by Mary Anning are from the early part of the early Jurassic. Plesiosaurus was a waste basket taxon so its stratigraphic range used to stretch all the way through the Jurassic and Cretaceous! But today there is only one valid species of Plesiosaurus, hence the more constrained temporal range for the genus.

Hi everyone, I'm the lead author of the Unktaheela paper. I've been part of the Dinosaur Toy Forum for years but don't post very often. But I'm happy to see this discussion about our research! Since some of you haven't been able to access the paper, I wanted to let you know that you can now read or download the entire thing for FREE before March 3 using this link!
https://authors.elsevier.com/a/1iQMaiVLDN60B

Ha, I literally just downloaded the paper before seeing your post here! Robin shared the link elsewhere.
I was just skimming through it, then googling images of the the black-legged seriema to see how the supraorbital process is expressed in life in that species.

Congratulations on the new paper, I'm looking forward to reading it fully, interesting discoveries!

Great!!! By the way, plesiosauria.com has been a great help to me over the years! Thanks for all you do!

[microraptorgui]

@microraptorgui Thank you so much for sharing a way to read it. And I love that artwork you did too.

You're welcome!