*just a warning: this is a pretty long post and will take some time to read, but it is definitely worth it...
Hello all,
Well, some may recall my post on
Carcharocles megalodon not too long ago; complete with photos of one of the largest teeth in my collection.
I had mentioned that I would post the rest of my teeth to illustrate the evolution of these elasmobranches from their common ancestor. I have complete lines for
Carcharocles megalodon as well as
Carcharodon carcharias (the Great White Shark).
So here it goes, enjoy!:
The first shark that started these two lineages (the Great-Great Granddaddy of them all) was
Cretolamna appendiculata (an extinct Mackerel Shark). This tooth is from the Eocene-Palaeocene Epochs and is approximately 50-65 million years old! These two teeth (upper and lower) were found in the Atlas Mountain Phosphate Pits in Khouribga, Morocco:
Notice the projections (cusps) on either side of the teeth and the lack of serrations on the blade, these are important morphological characteristics.
We'll do the
megalodon lineage (
Cretolamna appendiculata -
Carcharocles megalodon) first.
So, next in line was
Otodus obliquus:
.
These teeth have huge roots and no serrations and have retained the side-cusps. This particular tooth is from the early Eocene Epoch and is approximately 50-55 million years old. This tooth was found in the Atlas Mountains in Khouribga, Morocco.
Next was the first of the giant white sharks,
Carcharocles auriculatus. This tooth still exhibits the side cusps but notice that the blade is now serrated. This particular tooth is from the Eocene Epoch and is approximately 38-42 million years old! This tooth was found in the Castle Hayne Formation in North Carolina:
Next came
Carcharocles angustidens. I have a few pics to show you, first is from a juvenile shark:
Next one is from a small adult shark:
And the final tooth is somewhat of a transition tooth. You can see that the cusps are regressing and are being lost over evolutionary time. Only one cusp actually developed on this tooth and it is considerably small:
These three teeth are all from the early Miocene-Oligocene and are 15-30 million years old. They were all found in the Chandler Bridge Formation in Summerville, South Carolina.
After
C. angustidens came
C. chubutensis. You can see that there are no definite side-cusps on the teeth from this shark, only a residual curve where there used to be cusps:
This tooth is from the early to mid-Miocene Epochs and is 23-14 million years old. This is a very rare tooth from a land formation in Aurora, North Carolina.
And finally came the mighty
C. megalodon, the largest shark to have ever lived (as big as or bigger than a Greyhound Bus!):
Notice the complete loss of side-cusps. This tooth is from the mid-Miocene to Plio-Pleistocene Period and is 16-1.6 million years old.
The
megalodon was an evolutionary dead-end and left no descendants.
The next line of sharks that descended from
Cretolamna appendiculata (the first tooth pictured in this post) led to the Great White Shark.
After
C. appendiculata came
Isurus praecursor (an extinct Mako shark). This shark had teeth that were unserrated and had no side-cusps.
This tooth is from the late Eocene Epoch and is approximately 40 million years old. The tooth is from the Santee Limestone in Harleyville, South Carolina.
After
I. praecursor came
I. desori (the Shortfin Mako Shark).
This tooth is from the early Miocene Epoch and is approximately 13-15 million years old. The tooth was found in the Pungo River Formation in Aurora, North Carolina.
Next was
I. hastalis (another extinct Mako). This is a tooth from
I. hastalis:
Note the complete lack of serrations. This tooth is from the early Pliocene Epoch and is approximately 4.4 million years old. This tooth was found in the Yorktown Formation in Aurora, North Carolina. After
I. hastalis, there was a transitional species of Mako that is direct evidence for the evolution of the Great White from the
Isurus line of sharks. It just so happens that I have one of these teeth as well.
Notice the very beginning of serrations along the blade. This tooth is from the early Pliocene epoch and is approximately 4 million years old. It was found in the Huarra Formation in Antofagasta, Chile.
From this species came the Great White Shark (
Carcharodon carcharias):
Notice the serrations. This tooth is from the Pliocene Epoch and is approximately 3 million years old. The tooth is from the Huarra Formation in Antofagasta, Chile. This shark, of course, still exists today.
I hope you all enjoyed this little trip through time!
Cheers,
Ryan M Bolton
P.S. Here are all the described teeth back in their homes:
Threaded Mode