These are a few examples of the hypothesized Carcharocles Megalodon Evolution. I am sure some will chime in that not everyone agrees on this evolutionary chain, but I for one think it is very plausible (see below for some information on other suggested classifications). The teeth are from different location and are all in the 3.4 inch to 3.5 inch range. It took me quite a while to put this set of similar sized top quality teeth together.
From left to right (in chronological order):
1. Otodus obliquus : 3.5 inch tooth from Morocco. Lived during the Paleocene to Eocene epochs, about 60 to 45 million years ago.
2. Carcharocles auriculatus : 3.4 inch tooth from South Carolina. Lived during the Eocene epoch, about 55 to 45 million years ago.
3. Carcharocles angustidens : 3.4 inch tooth from South Carolina . Lived during the late Eocene to Oligocene epochs, about 45 to 28 million years ago
4. Carcharocles chubutensis : 3.4 inch tooth from Aurora, North Carolina. Lived during the Miocene epoch, about 26 to 15 million years ago.
5. Carcharocles Megalodon : 3.5 inch tooth from Georgia. Lived during the late Oligocene to early Pleistocene epochs, about approximately 28 to 1.5 million years ago.
Of interest in these photos would be the changes from Otodus (no serrations) to C. auriculatus (serrations), gradual evolutionary loss of the lateral cusps, and maintained chevron-shaped bourlette. You can also see the change in the root shape/contour and thickness over time. Thanks for looking!
If you are interested in the different evolutionary hypothesis for Megalodon and Great White sharks, like I am, you may occasionally get confused by the terminology and changing classifications. There are different trains of thought out there among marine paleobiologist and shark experts who seem to interpret the evidence differently and are always coming out with new information to support their classifications. Below is my attempt to summarize at least some of the major schools of classification for megalodon.
- Three main theories:
1. Order: Lamniformes -> Family: Lamnidae -> Genus: Carcharodon (ie. Carcharodon megalodon)
2a. Order: Lamniformes -> Family: Otodontidae -> Genus : Carcharocles (ie. Carcharocles megalodon)
2b. Order: Lamniformes -> Family: Otodontidae -> Genus : Otodus (ie. Otodus megalodon)
3. Chronospecies theory -> Carcharocles megalodon is one species that gradually evolved over time.
-Origin of "Megalodon": Megalodon teeth were first identified as shark's teeth by Danish naturalist, Nicolaus Steno, in 1667. It was not until 1835 that Swiss naturalist, Louis Agassiz, proposed the scientific name of Carcharodon megalodon in his research Recherches sur les poissons fossils (research on the fossil fish). In 1923 the genus Carcharocles was proposed by D.D. Jordon and H. Hannibal for classification of the auriculatus species (Carcharocles auriculatus) and later proponents suggested megalodon also should be included in this genus.
There is still debate about the placement of megalodon, with the some suggesting Megalodon is of close relation to modern great white sharks (ie. supporters of Family: Lamnidae, Genus: Carcharodon lineage). This is opposed by those who suggest that convergent evolution is responsible for the teeth similarities between megalodon and great whites and that megalodon is not closely related to modern great whites (ie. supports of Family: Otodontidae Genus: Carcharocles or Otodus lineage). Factoid: Convergent evolution is independent evolution of similar features in species of different lineages, creating analogous structure separately.
The "Family: Lamnidae, Genus: Carcharadon supports", tend to believe that both modern great white sharks and megalodon sharks come from a common ancestor, that some propose to be Palaeocarcharodon orientalis. The main reasons for this concept are phylogenic similarities in teeth of the two species in the opinion of these supporters. Other evidence these supported cite includes evidence that the internal calcification patterns of vertebrae from great white and megalodon sharks are similar enough to suggest the two are related. Also, some evidence in the fossil record suggests that megalodon sharks were present as far back as those of C. angustidens and C. chubutensis, thus suggesting megalodon was not a descendent of this line according to these supports.
The "Family: Otodontidae Genus: Carcharocles supporters", tend to suggest that megalodon is a descendant of Otodus obliquus, and that great white sharks had a separate and unrelated evolution from ancient mako sharks (ie. Isurus hastalis, the broad-tooth mako). These supports suggest that the similarities between great white and megalodon teeth are superficial at best and include some noticeable morphometric difference, with the one of the most noticeable probably being the chevron shaped bourlette that is absent in makos and great white teeth but present on megalodon and his proposed ancestors). The suggested lineage from this camp goes as follows : Otodus obliquus -> Otodus aksuaticus-> Carcharocles auriculatus -> Carcharocles angustidens ->Carcharocles chubutensis -> Carcharocles megalodon. Other supporters of this classification system agree with the evolutionary order but not the genus designation, as they do not recognize the need to use the genus “Carcharocles” described in 1923. These latter supports use the genus “Otodus” to describe Otodus obliquus and his subsequent descendents (ie. Otodus auriculatus, Otodus angustidens, Otodus chubutensis, Otodus megalodon).
Yet another evolutionary concept suggested by shark researcher , David Ward, is that megalodon is chronospecies. In this concept, Carchocles megalodon is in fact the only member of it’s evolutionary tree and is the same species as Otodus obliquus, C. auriculatus, C. angustidens, and C. chubutensis. The idea here is that Carcharocles megalodon was a single species that lived from the Paleocene to Pliocene Epochs and gradually changed during this time.
With all this said, I am the furthest thing from an expert, but from the evidence and literature I have read, I personally believe that Megalodon is part of the Otodus/Carcharocles lineage. I can also consider that it could be a chronospecies that gradually evolved over time, without the intermediates having a clearly defined "stop" of one species and “start” of another. This typically gradual change and adaptation is how I think of evolution anyway. It would make a funny cartoon strip though… with a picture of an ancient shark talking to a shark dentist who looks in his mouth and says “oh you must be a Carcharocles auriculatus by the looks of things”, and the shark replies back “No, I am a Carcharocles angustidens today, but yesterday I was a Carcharocles auriculatus”. Maybe I am the only one that thinks this would be funny? Anyway, I just don’t think it works like that. Who knows! I enjoy collecting them no matter how they are classified.