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Triassic placodontids
Topic Started: Jun 26 2013, 03:26 PM (81 Views)
DK1000
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In the absence of the Earth Prime T-Jr extinction, placodonts would be one of the weird Triassic critters that would be saved from extinction and continue to evolve. But just how far can they go? It wouldn't be a stretch of the imagination for them to continue on through the Hettangian, Sinemurian and Pliensbachian, but here is where things get more complicated.
As I have illustrated, the Earth Nova T-Jr extinction takes place between the Pliensbachian and the Toarcian, otherwise known as the 'Toarcian turn over'. As far as I'm aware, the 'Toarcian turn over' strongly affected aquatic life (and did not appear to have any bearing on terrestrial fauna), primarily hard-shelled invertebrates, such as molluscs and bivalves. Marine reptiles appeared to have came out seemingly unscathed by this event on EP, but on EN there is a different regime amongst the marine reptiles, in particular, the placodonts.
Considering the placodonts are highly-specialised for a durophagous lifestyle, they are particularly vulnerable in extinction events, and when their main source of food is hard-shelled invertebrates, it doesn't look like a happy ending for the placodonts. To me, it seems likely that the 'Toarcian Turn over' (the new T-Jr extinction) would be the placodonts ultimate demise. They survive for another 18.6 million years, but in the end it appears they're still doomed.

Though there may be a glimmer of hope for the placodonts; Henodus chelyops is unique among placodonts in that appears to live in brackish, if not freshwater, environments, and has adopted a novel way of feeding in placodonts, filter feeding. Other placodonts were specialised in being durophagous, while a filter-feeding Henodus is able to feed on any small particles of food it can swallow. Perhaps this more generalist diet (as well as a brackish and/or freshwater existance) would allow for other filter-feeding placodonts to pull through the new T-Jr extinction?

Thoughts? Discuss.
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the dark phoenix
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shelled organisms did not go completely extinct though, otherwise they would not exist today

with that logic in mind maybe a few other placodonts survived

say the seas are full of shellfish and about 50 placodont species, then a drop in shellfish population occurs and only about 10 species exist

so maybe they still exist but they are few in diversity
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DK1000
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the dark phoenix
Jun 26 2013, 08:11 PM
shelled organisms did not go completely extinct though, otherwise they would not exist today

with that logic in mind maybe a few other placodonts survived

say the seas are full of shellfish and about 50 placodont species, then a drop in shellfish population occurs and only about 10 species exist

so maybe they still exist but they are few in diversity
Shellfish were just as affected in the EP T-Jr extinction, and that was sufficient enough to kill off the shellfish eating placodonts, so the shellfish crash during the Toarcian turn over would affect the durophagous placodonts just as badly. Placodonts were doomed from the start, they were just too specialised and anything that affected their food supply is going to affect them severely.

And again, there's Henodus, it has a far greater chance of survival compared to the durophagous placodonts, it was a generalist filter feeder and lived in brackish and/or freshwater environments, if any kind of placodont was to survive the Toarcian turn over, it would be the Henodus-esque filter feeders.
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the dark phoenix
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well.....I got nothing..


what would adapt to refill the niche after this though?
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DK1000
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the dark phoenix
Jun 26 2013, 08:25 PM
well.....I got nothing..


what would adapt to refill the niche after this though?
What anything refill the niche in the first place? From what I can see, nothing moved into the durophagous lifestyle of placodonts until the Late Cretaceous, when the mosasaur Globidens evolved a similar lifestyle. Maybe that's what'll happen in MN, or perhaps some other strange Triassic critter could throw us a wildcard and evolve to fit that niche. I'm aware that some early icthyosaurs were designed for eating shellfish, perhaps some aberrant form of icthyosaur could take their place? More discussion is required on the subject.
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the dark phoenix
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DK1000
Jun 26 2013, 08:40 PM
the dark phoenix
Jun 26 2013, 08:25 PM
well.....I got nothing..


what would adapt to refill the niche after this though?
What anything refill the niche in the first place? From what I can see, nothing moved into the durophagous lifestyle of placodonts until the Late Cretaceous, when the mosasaur Globidens evolved a similar lifestyle. Maybe that's what'll happen in MN, or perhaps some other strange Triassic critter could throw us a wildcard and evolve to fit that niche. I'm aware that some early icthyosaurs were designed for eating shellfish, perhaps some aberrant form of icthyosaur could take their place? More discussion is required on the subject.
well I don't see lizards coming in so true mosasaurs are out

but I see pleurosaurids being a good replacement ^_^
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DK1000
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the dark phoenix
Jun 26 2013, 09:11 PM
DK1000
Jun 26 2013, 08:40 PM
the dark phoenix
Jun 26 2013, 08:25 PM
well.....I got nothing..


what would adapt to refill the niche after this though?
What anything refill the niche in the first place? From what I can see, nothing moved into the durophagous lifestyle of placodonts until the Late Cretaceous, when the mosasaur Globidens evolved a similar lifestyle. Maybe that's what'll happen in MN, or perhaps some other strange Triassic critter could throw us a wildcard and evolve to fit that niche. I'm aware that some early icthyosaurs were designed for eating shellfish, perhaps some aberrant form of icthyosaur could take their place? More discussion is required on the subject.
well I don't see lizards coming in so true mosasaurs are out

but I see pleurosaurids being a good replacement ^_^
Pleurosaurids as replacements for mosasaurs? Interesting concept, that deserves some looking into.
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the dark phoenix
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DK1000
Jun 26 2013, 09:17 PM
the dark phoenix
Jun 26 2013, 09:11 PM
DK1000
Jun 26 2013, 08:40 PM
the dark phoenix
Jun 26 2013, 08:25 PM
well.....I got nothing..


what would adapt to refill the niche after this though?
What anything refill the niche in the first place? From what I can see, nothing moved into the durophagous lifestyle of placodonts until the Late Cretaceous, when the mosasaur Globidens evolved a similar lifestyle. Maybe that's what'll happen in MN, or perhaps some other strange Triassic critter could throw us a wildcard and evolve to fit that niche. I'm aware that some early icthyosaurs were designed for eating shellfish, perhaps some aberrant form of icthyosaur could take their place? More discussion is required on the subject.
well I don't see lizards coming in so true mosasaurs are out

but I see pleurosaurids being a good replacement ^_^
Pleurosaurids as replacements for mosasaurs? Interesting concept, that deserves some looking into.
they look like mosasaurs with with legs and arms so all they need to do is develop flippers or just make the limbs webbed
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