Your favourite "living fossils"?

[Thunderbird]

We should be careful not to presume superficial phenotypic similarities are tantamount to genotypic near identity.:confused:

 

Such as the Hoatzin, bird at the top of the page?

[Mercedes Benzene]

My favorite is the Horseshoe Crab. Not only are they wicked cool-looking, but they've been really helpful in biomedical research! As a kid, I used to go to see them at the beach. Thousands would swarm the beaches, and I'd help flip them right-side-up when they got stuck on their backs. Good times.:confused:

Horseshoe crab - Wikipedia, the free encyclopedia

 

[mynah]

Thats kinda how I realized they were indeed dinosarus.

One day I was moving chickens from one pen to another for my father inlaw. I picked a chicken up and just looked at it. I said to my father inlaw that I had just realized that I was holding a dinosaur. He gave me a Look and said

" Its a chicken". like I was being an idiot.

Hen's (or rooster's) teeth are not as far-fetched as one might think.

 

Mutant chicken grows alligator teeth

 

Elsewhere, they have also been compared to dinosaur teeth. Apparently the genes for teeth are still intact, but something went missing upstream some 70 to 80 million years ago. As interesting to me would be why regaining teeth should be associated with severe defects leading to death in late embryonic development.

 

Speaking of animals with bills, let's not forget the monotremes, living remnants of a time when mammals still lay eggs and had milk, but no nipples.

[freeztar]

We should be careful not to presume superficial phenotypic similarities are tantamount to genotypic near identity.:unsure:

 

Indeed. Which were you referring to specifically?

[Eclogite]

Indeed. Which were you referring to specifically?

All of them, probably. The 'popular' ones definitely.

 

The star entrant for undergraduate palaeontologists is probably Lingula. It certainly has an excellent pedigree, being a genus of brachiopods from the Cambrian that continues to this day 'unchanged', we are told.

 

This turns out not to be the case. While the gross morphology and favoured environment have been constant there have been changes going on 'behind the scenes'. Thus the apatitic rods that form part of the shell have been replaced by botryoidal aggregates from Carboniferous times onwards. These brachiopods are evolving and have evolved, its just their gross appearance that seems unchanged. Their genetic make up is different and different in important ways.

 

It seems to me that the interest in finding 'living fossils' is one based more in romance than science. I see nothing wrong with that: fascination with the peculiarities of the universe is what attracts many of us to science, but we blind ourselves to important processes if we believe that living fossils are 'unchanged'.

 

Thunderbird, I am unfamiliar with the fascinating bird you have cited. Has it been found fossilised? If not we can scarcely call it a living fossil. I suspect - but await clarification from yourself - that it is a bird with primitive features. A bird has many of the genes that would let it develop even more reptilian characteristics than it already has. Rather than being a living fossil, this may be a retrogression.

[Moontanman]

All of them, probably. The 'popular' ones definitely.

 

The star entrant for undergraduate palaeontologists is probably Lingula. It certainly has an excellent pedigree, being a genus of brachiopods from the Cambrian that continues to this day 'unchanged', we are told.

 

This turns out not to be the case. While the gross morphology and favoured environment have been constant there have been changes going on 'behind the scenes'. Thus the apatitic rods that form part of the shell have been replaced by botryoidal aggregates from Carboniferous times onwards. These brachiopods are evolving and have evolved, its just their gross appearance that seems unchanged. Their genetic make up is different and different in important ways.

 

It seems to me that the interest in finding 'living fossils' is one based more in romance than science. I see nothing wrong with that: fascination with the peculiarities of the universe is what attracts many of us to science, but we blind ourselves to important processes if we believe that living fossils are 'unchanged'.

 

Thunderbird, I am unfamiliar with the fascinating bird you have cited. Has it been found fossilised? If not we can scarcely call it a living fossil. I suspect - but await clarification from yourself - that it is a bird with primitive features. A bird has many of the genes that would let it develop even more reptilian characteristics than it already has. Rather than being a living fossil, this may be a retrogression.

 

You are of course correct but I really don't think anyone who is talking about living fossils really thinks any animals alive today are genetically the same as a similar animal from even thousands of years ago much less many millions of years. I've always understood the term to mean animals that share common decent and are physically very similar to life forms from millions of years ago.

[Eclogite]

You are of course correct but I really don't think anyone who is talking about living fossils really thinks any animals alive today are genetically the same as a similar animal from even thousands of years ago much less many millions of years.

I fully accept that most - hopefully all - of the posters in this thread appreciate that fact, but what of the casual reader who is trying to learn a little biology from the posts. My point is that the distinction is not made with sufficient vigour for the idea to get across to everyone. That was my motivation for my somewhat tangential post.

 

Now we should return to our living fossils, where I join with several others in agreeing that birds are undoubtedly dinosaurs. And I ask, since some birds can speak, and some scientists claim that they can understand some of that speech, then how do we find evidence from the Cretaceous for talking dinosaurs?

[Thunderbird]

 

Thunderbird, I am unfamiliar with the fascinating bird you have cited. Has it been found fossilised? If not we can scarcely call it a living fossil. I suspect - but await clarification from yourself - that it is a bird with primitive features. A bird has many of the genes that would let it develop even more reptilian characteristics than it already has. Rather than being a living fossil, this may be a retrogression.

Probably so.. fascinating and telling nonetheless.

[Moontanman]

I fully accept that most - hopefully all - of the posters in this thread appreciate that fact, but what of the casual reader who is trying to learn a little biology from the posts. My point is that the distinction is not made with sufficient vigour for the idea to get across to everyone. That was my motivation for my somewhat tangential post.

 

Now we should return to our living fossils, where I join with several others in agreeing that birds are undoubtedly dinosaurs. And I ask, since some birds can speak, and some scientists claim that they can understand some of that speech, then how do we find evidence from the Cretaceous for talking dinosaurs?

 

Hmmm, talking dinosaurs? Maybe some of those odd objects that have come to light in mine shafts and other places are the result of a dinosaurian civilization?

[Turtle]

I'm doing an article on the topic, which is more directed towards the popular and high school market than most of the stuff I write, and wondered which animals, plants and other almost unchanged from the dawn of time organisms to include in a frozen-in-time top 10. ...

 

Uhmmmm.... I pick :turtle:'s of course.

[mynah]

There was a reason for the quotation marks in the title, and I certainly plan to clarify the issue in my article. As for the hoatzin, genetic studies confirm that it is somewhat remote from other birds, being basal to a large clade in which cuckoos, cranes, turacos, penguins and shorebirds are more closely related to each other than to the hoatzin.

 

Although not strictly a scientific concept, "living fossils' do contribute greatly to our understanding of evoltion as a result of making transitional characteristics and their underlying genetic mechanisms available for scientific study.

[Thunderbird]

There was a reason for the quotation marks in the title, and I certainly plan to clarify the issue in my article. As for the hoatzin, genetic studies confirm that it is somewhat remote from other birds, being basal to a large clade in which cuckoos, cranes, turacos, penguins and shorebirds are more closely related to each other than to the hoatzin.

 

Although not strictly a scientific concept, "living fossils' do contribute greatly to our understanding of evoltion as a result of making transitional characteristics and their underlying genetic mechanisms available for scientific study.

 

Thank you for the classification perspective on the hoatzin. I've been wondering about that.

[Thunderbird]

The Frilled Shark is a truly ancient species that has changed very little since pre-historic times—fossil evidence of the shark dates back to 95 million years. The shark is rarely seen alive since its natural habitat is over 1600 feet (488 meters) below sea level. Specimens have been found scattered around the globe, but the majority of Frilled Sharks have been found in Japanese waters.

The Frilled Shark resembles a giant eel more than a shark. However, the species possesses six gill slits, which identify it as a shark rather than an eel. The Frilled Shark has an upper jaw that is part of its skull, which is unique among living sharks. Most sharks living today have a hinged top jaw.

The Frilled Shark gives birth to live young and remains pregnant for as long as 3 1/2 years—the longest gestation period of any vertebrate known on Earth

 

 

 

 

Rare, Prehistoric Frilled Shark in Japan http://video.google.com/videoplay?docid=1152989587849410416

[Thunderbird]

The Vampire Squid

 

Just as the horseshoe crab is not actually a crab, the vampire squid is not a squid, but a distant cousin descended from a cephalopod no longer with us, so that it occupies its own taxonomic order. And as the fossil record for coelacanths is spotty because of their deep habitat, so too is the record for the vampire squid, which makes it home at nearly 3,000 feet under the sea, a depth at which the concentration of oxygen hovers around 3 percent, the absolute limit for aerobic metabolism. Unlike squids and octopuses, it has no ink sac, but rather the ability to eject a bioluminescent mucus meant to distract predators in the near absolute darkness of its habitat. Because it lives at such extreme depths, it has evolved to survive through the least possible expenditure of energies. Whereas an octopus would ink a predator and jet away quickly, the vampire squid prefers to slink off just out of view. http://www.popsci.com/scitech/gallery/2008-07/living-fossils

 

 

[Turtle]

My bad! :doh: I see it is de rigueur to support one's vote for favorite living fossil. I give you, Testinades!!

Turtles all the way down. :hihi:

:eek2:

:hihi::hihi: :lol::doh:

Turtle - Wikipedia, the free encyclopedia

...The earliest known turtle is proganochelys, though this species already had many advanced turtle traits, and thus probably had many millions of years of preceding "turtle" evolution and species in its ancestry. It did lack the ability to pull its head into its shell (and it had a long neck), and had a long, spiked tail ending in a club, implying an ancestry occupying a similar niche to the ankylosaurs (though only through parallel evolution). ...

[Moontanman]

Turtles are very cool, I have four I keep as pets, one was born in my care ten years ago the others I've had from 20 to 35 years. Turtle, you have my old nick name, from when I was in high school. I once made the school bus driver stop and let me get a box turtle off the road so they called me turtle from then on.

[Eclogite]

Conservative politicians in the UK.