Troodon no longer a valid genus: Latenivenatrix and Stenonychosaurus replace it

[Sim]

This whole thing feels very pandering to me, it doesn't make the actual specimens any easier to understand or recognize. I would think Troodon is widely enough used to be a nomen protectum.

It isn't pandering.  It's highlighting the fact that Troodon formosus, and consequently Troodon as a whole, as a classification means nothing.  The type of tooth Troodon formosus is based on is found in a number of different troodontid genera, including both North American and Asian genera, which lived millions of years apart.  The species in these genera all have valid scientific names based on diagnostic remains.  There's nothing that shows the Troodon formosus holotype tooth is from the same species as any of these.  All of these valid species don't even come from the same formation as the Troodon formosus holotype tooth!  Troodon formosus has been shown to be an invalid nomen dubium by definition.  It's the correct scientific way of dealing with this, and I think it's been overdue.

According to this Wikipedia page, becoming a nomen protectum doesn't apply to Troodon's situation: https://en.wikipedia.org/wiki/Nomen_oblitum

Regarding what you said about it not making the specimens easier to understand/recognise...  Identifying features for the specimens have been given.  (I've only read the paper's abstract page though, as the rest of it is behind a paywall.  For the additional information I've been reading what fairly reliable sources have been saying about it online.)  It's also brought attention to the reality of what Troodon is.  Troodon has become the most famous member of its family, but the famous perception of Troodon has come from subsuming a number of species with different qualities into it.  What has been shown now is that Troodon really is just the name attached to a type of tooth from the Judith River Formation, a type of tooth that is now known to be present in a number of valid troodontid genera.

Troodon has a history of being a highly unstable classification, and creating incompatible classifications when other species are included within Troodon.  One example: Back when troodontids were thought to be what are now known as pachycephalosaurids, Stegoceras and Pachycephalosaurus were classified as species of Troodon.  Even while Troodon has been recognised as a member of the same family as Saurornithoides and Stenonychosaurus this kind of confusion has continued: A number of troodontid species were included within Troodon, while others were agreed to not be in this genus but they possess the single feature (the type of tooth) that was meant to identify the one species Troodon is based on.  I think it's become clear now that the Troodon holotype tooth is unable to show what species it comes from, and that trying to prop up Troodon by including better-represented species within it only causes problems.

[Lusotitan]

A neotype designation could definitely made (just look at Coelophysis), but I'd rather it didn't. Troodon has a long and complicated history and anybody who heard the name would probably think of the long defunct super-lumed version instead whatever new specimen we tie the name to. Trying to keep a name that was problematic in the first place that has so much historical baggage is, in my eyes, a very bad idea.

[Dinoguy2]

As for the BotM Troodon, my guess is it's based on the Egg Mountain specimens? Which will probably get a new genus eventually.

Edit: actually I'm sure it was based on Hartman's skeletal, which I think is a hybrid between Stenonychosaurus and Latenovenatrix. So it's either a chimera or could be a stand in for either one.

Latenivenatrix is based partly on new material, but the old material was already more complete than the Stenonychosaurus remains. So it's safe to say that most pictures of "Troodon" are actually Latenivenatrix, rather than Stenonychosaurus.

[Faelrin]

Thanks. I guess I'll have to get used to this. Might use mine as a stand in for Stenonychosaurus since that was the one contemporary with Dromaeosaurus I think? Although I wonder why they did not go the Iguanodon route with the Troodon name? Too complicated? I guess Troodon can join the nomen dubium club with Monoclonius and Trachodon, etc, now.

[Dinoguy2]

Thanks. I guess I'll have to get used to this. Might use mine as a stand in for Stenonychosaurus since that was the one contemporary with Dromaeosaurus I think? Although I wonder why they did not go the Iguanodon route with the Troodon name? Too complicated? I guess Troodon can join the nomen dubium club with Monoclonius and Trachodon, etc, now.

The Iguanodon thing was just bad from every angle. There's no way the "new" Iguanodon would even be considered the same genus as the original, let alone species. It's from a different time and place and country!

[Shadowknight1]

Am I the only one that will still call the darn things Troodon anyways?  Heck, I'll never call Brachiosaurus "Giraffatitan".

[Neosodon]

Am I the only one that will still call the darn things Troodon anyways?  Heck, I'll never call Brachiosaurus "Giraffatitan".

Brachiosaurus and Giraffatitan a different species though right? Troodons remains have been assigned to other species though. But it would have been nice though if they just assigned the name to one of the new dinosaurs instead if making up new names. But hey, what paleontologist wouldn't want to name a new dinosaur.

[Faelrin]

Thanks. I guess I'll have to get used to this. Might use mine as a stand in for Stenonychosaurus since that was the one contemporary with Dromaeosaurus I think? Although I wonder why they did not go the Iguanodon route with the Troodon name? Too complicated? I guess Troodon can join the nomen dubium club with Monoclonius and Trachodon, etc, now.

The Iguanodon thing was just bad from every angle. There's no way the "new" Iguanodon would even be considered the same genus as the original, let alone species. It's from a different time and place and country!

I meant the whole Mantellodon thing that happened. Am I correct in understanding that specimen was discovered and named Iguanodon first? I get things were weird back then, and often clumped together, but why did the later specimens belonging to I. bernissartensis keep that name, and not that one that was discovered and named prior? Could the same then not be done with Troodon? Granted I don't really understand how or why these things work the way they do.

[Takama]

Am I the only one that will still call the darn things Troodon anyways?  Heck, I'll never call Brachiosaurus "Giraffatitan".

Those are two diffrent animals from diffrent parts of the world

Girraffatitian was a African animal While Brachiosaurus was a larger, American one. Its just at one time, they were both thoght to be a species of Brachiosaurus. just like a lion and a tiger are species of Panthera.

But Brachiosaurus was longer in the torso then Girafatitian, and i belive there Skulls are diffrent as well.

[CityRaptor]

Well, it makes sense. Fifteen million years is a pretty long time for a genus. Seems to be a general trend that a more advanced genus is shorter lived than a basal one.

[WarrenJB]

But it would have been nice though if they just assigned the name to one of the new dinosaurs instead if making up new names. But hey, what paleontologist wouldn't want to name a new dinosaur.

Stenonychosaurus isn't new though. It might've been a slightly bigger tangle if that name - or to pick a more famous example, Brontosaurus - had been reassigned to different remains when they became synonymised with Troodon and Apatosaurus respectively, before they were declared valid genera again. It's a reason for keeping the name Troodon on the shelf. As Tim Williams said on the DML:

But the authors provide some hope for _T. formosus_, if future
material from the same formation and locality can be referred to this
species...

"Although the validity of _Troodon formosus_ may be contentious,
future discoveries may provide the osteological information required
to sort out true relationships in North American troodontids. For any
specimens that are positively identified as _Troodon formosus_,
however, they must originate from the Judith River Formation in the
region from where the holotype was recovered."

Maybe.  The implication is that new diagnostic material could be
referred to _T. formosus_ to keep it alive as a valid taxon.  But it's
not that simple.  Even if troodontid material is recovered from the
JRF that includes diagnostic bones along with teeth that match _T.
formosus_, it may not be enough to save _T. formosus_.  A neotype
would probably have to be designated for _T. formosus_ based on this
new (topotypic?) material.  This could happen, but there's no
guarantee it will (even if potentially referrable material is
discovered).

dml.cmnh.org/2017Aug/msg00045.html

As for Latenivenatrix, at about half as long again and I guess roundabout six times the mass(?) of the next biggest NA troodont (barring our friend in Alaska) it seems a pretty fair bet that it's something a bit different to the owner of the Judith River tooth.

(And the Iguanodon/Mantellisaurus thing hurts my head. For that alone I'm willing to go with Latenivenatrix, even if I still have to think for a moment before hitting the N, V, and vowel keys)

[Sim]

Am I the only one that will still call the darn things Troodon anyways?  Heck, I'll never call Brachiosaurus "Giraffatitan".

Brachiosaurus and Giraffatitan a different species though right? Troodons remains have been assigned to other species though. But it would have been nice though if they just assigned the name to one of the new dinosaurs instead if making up new names. But hey, what paleontologist wouldn't want to name a new dinosaur.

Stenonychosaurus isn't a new name.  The remains didn't belong to Troodon in the first place, they were originally classified as belonging to Stenonychosaurus.  Philip Currie synonymising Stenonychosaurus with Troodon in 1987 basically resulted in the fame and remains Stenonychosaurus was known from being taken from it and given to Troodon, undeservedly since it couldn't be shown with any certainty the Stenonychosaurus remains and the Troodon tooth were from the same species/genus, the two don't even come from the same formation.  Troodon famously being the fairly small, intelligent theropod with the foot sickle claw was born from this, it's entirely based on replacing the name of Stenonychosaurus with Troodon.  The specimens that were classified as belonging to Stenonychosaurus have now been found to represent two species, one is Stenonychosaurus, and the other was new which has been named Latenivenatrix.

[Neosodon]

Am I the only one that will still call the darn things Troodon anyways?  Heck, I'll never call Brachiosaurus "Giraffatitan".

Brachiosaurus and Giraffatitan a different species though right? Troodons remains have been assigned to other species though. But it would have been nice though if they just assigned the name to one of the new dinosaurs instead if making up new names. But hey, what paleontologist wouldn't want to name a new dinosaur.

Stenonychosaurus isn't a new name.  The remains didn't belong to Troodon in the first place, they were originally classified as belonging to Stenonychosaurus.  Philip Currie synonymising Stenonychosaurus with Troodon in 1987 basically resulted in the fame and remains Stenonychosaurus was known from being taken from it and given to Troodon, undeservedly since it couldn't be shown with any certainty the Stenonychosaurus remains and the Troodon tooth were from the same species/genus, the two don't even come from the same formation.  Troodon famously being the fairly small, intelligent theropod with the foot sickle claw was born from this, it's entirely based on replacing the name of Stenonychosaurus with Troodon.  The specimens that were classified as belonging to Stenonychosaurus have now been found to represent two species, one is Stenonychosaurus, and the other was new which has been named Latenivenatrix.

Well the Troodon name could just be assigned to Latenivenatrix.

[Dinoguy2]

Am I the only one that will still call the darn things Troodon anyways?  Heck, I'll never call Brachiosaurus "Giraffatitan".

Brachiosaurus and Giraffatitan a different species though right? Troodons remains have been assigned to other species though. But it would have been nice though if they just assigned the name to one of the new dinosaurs instead if making up new names. But hey, what paleontologist wouldn't want to name a new dinosaur.

Stenonychosaurus isn't a new name.  The remains didn't belong to Troodon in the first place, they were originally classified as belonging to Stenonychosaurus.  Philip Currie synonymising Stenonychosaurus with Troodon in 1987 basically resulted in the fame and remains Stenonychosaurus was known from being taken from it and given to Troodon, undeservedly since it couldn't be shown with any certainty the Stenonychosaurus remains and the Troodon tooth were from the same species/genus, the two don't even come from the same formation.  Troodon famously being the fairly small, intelligent theropod with the foot sickle claw was born from this, it's entirely based on replacing the name of Stenonychosaurus with Troodon.  The specimens that were classified as belonging to Stenonychosaurus have now been found to represent two species, one is Stenonychosaurus, and the other was new which has been named Latenivenatrix.

Well the Troodon name could just be assigned to Latenivenatrix.

Not a good idea - the Troodon teeth and the Latenivenatrix skeleton come from different formations.

There are no good, non-teeth troodontid remains from the same formation of Troodon. So it's possible, maybe even likely, that Troodon is in fact a distinct species different from both Latenivenatrix and Stenonychosaurus and Talos and whatever the Alaskan and Two Medicine species will get named. But that's the whole problem, because right now, Troodon is a dinosaur known only from teeth and nothing else, so we know zero about its appearance.

[Neosodon]

Am I the only one that will still call the darn things Troodon anyways?  Heck, I'll never call Brachiosaurus "Giraffatitan".

Brachiosaurus and Giraffatitan a different species though right? Troodons remains have been assigned to other species though. But it would have been nice though if they just assigned the name to one of the new dinosaurs instead if making up new names. But hey, what paleontologist wouldn't want to name a new dinosaur.

Stenonychosaurus isn't a new name.  The remains didn't belong to Troodon in the first place, they were originally classified as belonging to Stenonychosaurus.  Philip Currie synonymising Stenonychosaurus with Troodon in 1987 basically resulted in the fame and remains Stenonychosaurus was known from being taken from it and given to Troodon, undeservedly since it couldn't be shown with any certainty the Stenonychosaurus remains and the Troodon tooth were from the same species/genus, the two don't even come from the same formation.  Troodon famously being the fairly small, intelligent theropod with the foot sickle claw was born from this, it's entirely based on replacing the name of Stenonychosaurus with Troodon.  The specimens that were classified as belonging to Stenonychosaurus have now been found to represent two species, one is Stenonychosaurus, and the other was new which has been named Latenivenatrix.

Well the Troodon name could just be assigned to Latenivenatrix.

Not a good idea - the Troodon teeth and the Latenivenatrix skeleton come from different formations.

There are no good, non-teeth troodontid remains from the same formation of Troodon. So it's possible, maybe even likely, that Troodon is in fact a distinct species different from both Latenivenatrix and Stenonychosaurus and Talos and whatever the Alaskan and Two Medicine species will get named. But that's the whole problem, because right now, Troodon is a dinosaur known only from teeth and nothing else, so we know zero about its appearance.

Ah, so Troodon may still exist. Just as another mystery dinosaur we know almost nothing about.

[Reptilia]

That could be another case like Spinosaurus, a very popular name that most people don't know we actually know very little about. Although a bit more on the extreme side, cause there's only a tooth here. I wonder what could happen if future finds would prove that such tooth belonged to a completely different kind of animal, not a troodontid at all. Would the name Troodon remain valid, and would the name Troodontidae remain valid for the family?

[The Atroxious]

To be honest, I've strongly suspected that this would happen for a while now. There was just too much ambiguity going on with genus Troodon for me to have faith in its staying power, what with unrelated or very loosely related fragmentary remains being assigned to it. Literally, the genus was formed because some guy was like, "Hey, I found some weird looking teeth from one specimen, and a weird looking foot from another, I'm going to synonomize them because weird features go together, right?"

I never liked the genus Troodon for a number of reasons besides, so I'm rather happy with the reinstatement of Stenonychosaurus.

[PaleoMatt]

So what will hapoen with the unidentified larger Alaskan species?

[WarrenJB]

Since Troodon doesn't exist anymore, they'll have blinked out of our reality, with the only mark of their passing being a small popping sound as air refills the vacuum left by their disappearance.

That, or they'll get their own taxon sooner or later, when someone becomes bored of calling it 'the (giant) Alaskan troodontid'.

[Dinoguy2]

So what will hapoen with the unidentified larger Alaskan species?

They'll get their own genus and species. But we knew that already, because nobody actually thought they were the same thing as T. formosus.