Відео

You are correct in that the modern sharks we know today (the Galean and Squalean Sharks) aren’t known earlier than the Early Jurassic, though true selachians date back to the Early Permian with Synechodus antiquus. You are also right that true sharks (selachians) did coexist with hybodonts and ctenacanths. Ctenacanths in the Mesozoic are questionable (in my opinion the Cretaceous “ctenacanths” are likely selachians convergently evolving similar teeth), though they certainly coexisted at the same time as the earliest Synechodus. On this list, some are more distant relatives to sharks, falling under Euchondrocephali, whereas others are closer related to sharks, also belonging within Elasmobranchii. I hope this helps!

Haha perhaps a haircut would be welcomed in the near future

Many of these and other extinct sharks and relatives are known from articulated body fossils, which is where many of these renderings are based off of. Teeth are by far the most common fossils found from these animals (their cartilaginous skeletons don’t easily preserve, whereas their teeth do and are shed frequently), but that does not mean more complete remains of either that exact species, or close relatives, weren’t also discovered, which can allow artists to reconstruct what these animals may have looked like.

@@elasmocast the problem is the skeleton doesn’t show the whole picture. You could ask 2 artists to recreate it and get vastly different results. My issue is with science being unscientific. When they say it is some way, or treat something as a fact when at best, it’s their best educated guess. Just like dinosaurs, were they lizards or birds? They used to be depicted one way, and that’s “how it is” and now it’s different, yet the fossils never changed. Science is about observation and experiments. Don’t sell me your imagination.

Yes you are right, skeletons don’t show everything, and I agree, I also dislike the ‘unscientific’ recreations that are sometimes created without much factual backing. Some dinosaurs, for example, we have a fairly solid idea of what they would’ve looked like when they were alive; when an entire animal is constructed off of a partial fossilized femur I get very skeptical lol. I think that some older models that, while now known to not be accurate, aren’t necessarily unscientific. A lot of times reconstructions are created off of the available scientific information observed by the time, and become outdated not because of them making stuff up out of thin air, but because new discoveries wind up shedding light on new aspects previously unthought of. In my opinion, in good paleo art there’s a combination of as much scientific accuracy as possible blended with realistic creativity.

Haha I can see it!

Haha I get that all the time!

It’s several different venues laid out all throughout the city of Tucson, Arizona. A great place to go for any fossil enthusiast!

Thank you so much, I appreciate the kind words!

Thank you, we agree!

Very true. It took me years to find my first tooth here in Arizona! I would love to eventually hunt for arrowheads, if only the law’s weren’t so stringent on them in this state.

@@elasmocast I’m in Missouri but I look mostly on private land. If it’s on private it’s pretty much fair game. Most rivers and creeks have arrowheads in them here and it is usually within the law if they are on the gravel bars. The fossils here at least where I look are fairly hard for me to find. I’m sure they are there but other states are better as far as I know. Southern Missouri was a marsh I think millions of years ago but I’m in mid Missouri above the water line I think

Private land is the safest way to go for sure. If I recall correctly most of the chondrichthyan teeth I’ve seen from Missouri are from the Paleozoic, and finding those is a very different experience than how, for example, many collectors from the Southeast collect theirs.

That largest one is a very respectable size for a megalodon tooth! This is definitely a place I’d recommend fossil and mineral lovers to attend at least once.

Thank you! Those teeth in question are of Otodus obliquus and were recovered in the phosphate mines around Khouribga, Morocco. Hope this helps!

Hola que bello lugar a mi me encantan los fósiles en que parte se encuentra

There’s definitely some matrix on this specimen. At first I thought it was situated on top of the vertebrae, but upon closer inspection it looks as though the matrix is embedded within the vertebrae’s arch!

🦞

@@Rex_Thegentleman 🦑

Haha it’s a very well-named shark!

Glad you enjoyed the video, and thank you for the subscription!

Haha right! And thank you!

Thank you for your constructive feedback!

It’s a great site!

Indeed!

@@elasmocast Yes!

Haha good point!

A gambler that lost is a loser! Haha Palaeocarcharodon did evolve too early for its own good; it’s crazy to think about all of the evolutionary possibilities if events had unraveled differently.

I think that length of time within a particular niche and success in that niche would constitute whether a shark is a winner or loser. A successful generalist has greater potential for abundance and duration throughout time, making them an evolutionary winner.

Xenacanths became rapidly diverse and were apex predators in certain ecosystems such as freshwater environments, so I would consider them a winner, even though they aren’t very successful after the End-Permian Mass Extinction and become extinct in the Triassic.

We’re glad you enjoyed it!

Yessir!

That’s understandable! It is a huge evolutionary feat going from Otodus obliquus to Megalodon. I am in agreement with you that Otodus megalodon isn’t the best placement for the shark.

Thank you, and yes, having prior understanding to biological terminology would make it a much easier watch!

I’m glad you found the video informative!

That’s fair enough!

I’m trying my best:(

@@elasmocast your vids are good and im here for you but you look so sad

@@Reece983 I appreciate that and thank you for your concern!

Thank you, and glad you found it informative!

Thank you, Howard!

Thank you, Will!

Thank you, it means a lot!

Thank you, very much appreciated!

It is really interesting how diverse Chondrichthyans became in the Late Paleozoic, and how events like the end-Permian extinction event drastically bottlenecked diversity. We do have great species-diversity today, but broader-group level diversity is a mere fraction of what it was before in the Late Paleozoic.

A lot of people tend to have most experience with teeth from the Late Cretaceous onwards. With that said, the bizarre Chondrichthyans alive before then are, in my opinion, some of the most interesting taxa out there. Xenacanth teeth and Edestus tooth whorls are prime examples of that. It’s really fascinating thinking about the incredible diversity in Chondrichthyan history!

Hello Howard, that’s a great idea! I can think of lots of formations off the top of my head that would be great candidates for something like that.

Thank you! That’s a great idea; I did take with me a sandwich bag full of loose sediment to look through at home, but ideally taking more would be better so I don’t have to spend the time and money traveling back and forth to the site.

The Paleozoic had some of the craziest Chondrichthyans of all time, and were far more diverse than what we have today, on a broader group-level basis.

Oh believe me, I did that!

Thank you! I was not expecting to find one of those, especially in that condition.

Thank you, and that’s a great idea! Pathological teeth can be incredible in both their oddities and uniqueness!

Those are strange ones!

Thank you, and that’s a great idea!

We’re glad you found this video informative!

Those Hemipristis sound interesting! Taphonomy can make some teeth difficult to make solid determinations off of. What book did you find? We’re looking forward to you making a video on them!

@Elasmocast Yeah. they were definite Hemipristis teeth I dug up in mid miocene creek, definitely Hemipristis serra (tho I have a gut feeling it can be hard to know if there were subspecies, based on teeth alone). If only soft tissue could readily preserve lol, lots of taxonomy issues could readily be resolved and new evolutionary insights. But is still amazing what ocassional body impression fossils are out there, for sure The quality book is called "Discovering fossil fishes" by John Maisey. Didnt read all of it, I had plenty of books to look over and find what interested me, but I know for sure I'll find it again sooner or later

Thank you for your feedback! We will try to simplify terminology and explain complex terms more effectively as we become more experienced with UA-cam.