Mako To Great White

[DeloiVarden]

As I went to stick my new lower great white tooth into my riker box, I noticed something that hadn't occured to me. This new tooth looked a lot like one of my existing makos found a few months back. I have seen side by side comparisons of great white and mako teeth highlighting the theory that great white evolved from mako, but hadn't found any good examples myself until now. As you can see in the photos, they are very similar in shape and thickness, except the right one (GW) has serrations. I thought it would be interested to start a thread on the topic, so if you have any good examples yourself, feel free to post them in this thread.

[Gizmo]

Here's a super rare transitional mako I found recently in the St. Mary's Formation in Maryland.

-1 1/4 inches

[Paleoc]

Very, very nice.

There is a reason for my avatar. If you enlarge the modern GW tooth 3 times, you can readily see the resemblance. In addition, I have 2 more images with the hastalis teeth on the left and the great whites on the right.

[DeloiVarden]

Nice transitional Gizmo and awesome examples Paleoc!

[Sharkbyte]

The comparison between the two are very interesting. Nice teeth by everyone.

[RickNC]

The two teeth are virtually identical minus the serrations.

[THobern]

Here's one from Chile. 2 7/8", no repairs.

[Life 42]

So if I am seeing this right, I can add some serrations to my Mako and finally have the great white that I covet?

:jig:

Edited October 16, 2011 by Life 42

[Paleoc]

Here's one from Chile. 2 7/8", no repairs.

Very nice

[fossilselachian]

Jason:

Here are a few other examples where only the presence/absence of serrations identify the species.

My mistake!! I reversed the state locations on the second pic.

Edited October 16, 2011 by fossilselachian

[DeloiVarden]

Super sweet examples as usual fossilselachian! Jason

[MikeDOTB]

So if I am seeing this right, I can add some serrations to my Mako and finally have the great white that I covet?

:jig:

Cutting serrations into a perfect mako shark tooth is cheating!

Anyways, interesting examples everyone.

[Dent de requin]

Very good idea, here are two tooth comes from Chile, they measure 1.8 inches

[MikeDOTB]

Here's a super rare transitional mako I found recently in the St. Mary's Formation in Maryland.

-1 1/4 inches

Wow, with cusps!

[cowsharks]

What formations have both mako's and great white's been found in "together"?

Daryl.

[erik m]

Here's a super rare transitional mako I found recently in the St. Mary's Formation in Maryland.

-1 1/4 inches

Maybe you should think more to a isurus escheri.

Escheri teeth are fond more with sidecusps.

[siteseer]

Cowsharks,

That's a good question. It's tricky because it's important to keep track of which parts of the formation (down to which beds) each tooth form is coming from. Often, teeth from different beds are found scattered in the same area of a desert or mixed on the same river bottom. It's not always easy or possible to trace the each tooth form (the unserrated one, the weakly-serrated one, the fully-serrated one) to its source bed (perhaps completely eroded away in that area) but it has been done for certain transitions at certain sites (for Otodus-Carcharocles in the Middle-Late Eocene of Kazakhstan; for Isurus or Cosmopolitodus-Carcharodon in California, Peru, and Chile).

Generally, you don't find an unserrated Isurus hastalis in the same bed with a fully-serrated Carcharodon carcharias though hastalis has been reported as surviving into the Early Pliocene of southern California. It would be interesting to see those teeth and what the latest determination is of the source bed (possibly reworked material or revised age). Years ago, I had the opportunity to sort out a rather large sample of Early Pliocene shark teeth from the San Mateo Formation in a private collection (a beer flat full - maybe several hundred/one thousand teeth). I found weakly-serrated teeth and fully-serrated teeth which probably came out of separate beds. It should be added that a number of juvenile-subadult teeth were in the sample. Even today, the teeth of newborn/juveniles are sometimes unserrated-weakly serrated. I found some Isurus oxyrinchus teeth and a few teeth that I thought might be hastalis until I compared them to modern oxyrinchus jaws. In the end I found no hastalis in the sample.

You can find hastalis in the lower part of the San Mateo but the great whites have been found only in the upper part and there appears to be a time break of a few million years between the deposition of those parts. I believe it is a similar situation with the Pisco Formation in Peru and the Bahia Inglesa Formation in Chile.

Jess

What formations have both mako's and great white's been found in "together"?

Daryl.

[Auspex]

...I believe it is a similar situation with the Pisco Formation in Peru and the Bahia Inglesa Formation in Chile.

There is a discontinuity in the deposition in these two formations?

[siteseer]

Chas,

I took some time to look into that. According to Walsh and Hume (2001) the Bahia Inglesa does range from Late Miocene to Mid-Pliocene in age but there is not an unconformity to mark a break in sedimentation. Also, the bonebed that contains hastalis teeth also contains C. carcharias. However, it is not made clear whether one species is found at separate levels within it, though the authors stated, "Since the bonebed is partially Miocene in age based on the presence of C. hastalis, the base of Unit 2 must be Late Miocene." In the article "Unit 2" is the bonebed. An age range is not given for the bonebed but it is placed at the Miocene-Pliocene boundary.

A slightly more detailed account of the bonebed can be found in Walsh and Naish (2002). It is stated that dating the bonebed is problematic due to the lack of calcareous fossils and rarity of well-preserved siliceous microfossils. The article restated the presence of hastalis and carcharias but added that the "unit must represent a condensed sequence that spans both the Miocene and Pliocene" with hastalis being the most abundant shark teeth "whilst those of Carcharodon carcharias are comparatively rare" suggesting that the bonebed does not extend very far into the Pliocene. Does the use of the word "condensed" mean that the bonebed is missing time (sedimentation) somewhere (and perhaps at more than one level) from its base to top? That must be why I thought there was a break but the authors did not say it outright. I don't think such a hiatus, if it did occur (once or more) would have been very long (maybe measured in tens of thousands of years?). Maybe someone else has more updated information on that.

The Pisco does contain an unconformity above which C. carcharias is found but not hastalis (see Muizon and DeVries, 1985).

Jess

Muizon, C. de. and T.J. DeVries. 1985.

Geology and paleontology of late Cenozoic marine deposits in the Sacaco area (Peru). Geologische Rundschau, 74. 547-563.

Walsh, S.A. and J.P. Hume. 2001.

A new Neogene avian assemblage from north-central Chile. Journal of Vertebrate Paleontology, 21, 484-491.

Walsh, S. and D. Naish. 2002.

Fossil seals from late Neogene deposits in South America: a new pinniped (Carnivora, Mammalia) assemblage from Chile. Palaeontology, 45(4): 821-842.

There is a discontinuity in the deposition in these two formations?

[Auspex]

Jess,

Thanks for putting so much time and effort into researching and clarifying that!

I have wondered whether the existence of (some) marine bone beds might not indicate some reworking during periods of low deposition?

[Boesse]

WRT the Bahia Inglesia locality, Walsh and Martill (2006) did a much more detailed taphonomic and sedimentologic study of the bonebed. It appears to be time transgressive (having eroded into strata of different ages in different places), widespread, and it is unclear how much strata has been "cannibalized". The problem is, not all of the specimens have been collected from the bonebed - some material is from above or below it. A bonebed like this could have easily cannibalized a couple million years worth of strata, especially if the age of the underlying strata (and thus the age of strata that were eroded) changes along strike.

Walsh, S. A., and D. M. Martill. 2006. A possible earthquake-triggered mega-boulder

slide in a Chilean Mio-Pliocene marine sequence: evidence for rapid uplift and bonebed

genesis. Journal of the Geological Society, London 163:697-705.

[Auspex]

Thanks Bobby (Oh Mighty Rock Whisperer)!

It seemed to me that an accurate temporal interpretation of the stratigraphy would be important to the whole transitional shark species thing (though I admit I had ulterior motives for my inquiry).

[siteseer]

Bobby,

Yes, thanks for that update. I did not know about that article.

Jess

P.S. Best wishes to Mr. and Mrs. Boessenecker. Congratulations on your acceptance to the program. Work hard and have fun in NZ but don't be a stranger.

WRT the Bahia Inglesia locality, Walsh and Martill (2006) did a much more detailed taphonomic and sedimentologic study of the bonebed. It appears to be time transgressive (having eroded into strata of different ages in different places), widespread, and it is unclear how much strata has been "cannibalized". The problem is, not all of the specimens have been collected from the bonebed - some material is from above or below it. A bonebed like this could have easily cannibalized a couple million years worth of strata, especially if the age of the underlying strata (and thus the age of strata that were eroded) changes along strike.

Walsh, S. A., and D. M. Martill. 2006. A possible earthquake-triggered mega-boulder

slide in a Chilean Mio-Pliocene marine sequence: evidence for rapid uplift and bonebed

genesis. Journal of the Geological Society, London 163:697-705.

Edited October 21, 2011 by siteseer

[Boesse]

Hey, thanks Jess! Don't worry, I haven't forgotten about that email. I was up at Point Reyes doing fieldwork at the time, and haven't had enough time to sit down and think about it.

While tangentially on the subject of the Purisima Formation and fossil sharks - there are several parts of the Purisima Formation where the Cosmopolitodus-Carcharodon transition can be "seen", one of the few spots in California, and perhaps the best in terms of age constraints on the various samples.

Cosmopolitodus hastalis (found in most fossiliferous Miocene marine rocks of California)

1) Base of the Purisima Fm., 6.9 Ma - Cosmopolitodus teeth

2) Slightly above the basal contact - 6.9-5.6 Ma - a sample of Cosmopolitodus teeth, with one faintly serrated specimen

"Transitionals"

3) In a section of the Purisima in a different locality, but dated to 6.2-5.4 Ma - two "transitional" Carcharodon sp. teeth with minute serrations.

4) In another northern section of the Purisima, dated at younger than 5.2 Ma (this age determination might be too young, and it is an older estimate), there is a decent sample (~10 teeth) of "transitional" Carcharodon sp. teeth, also with minute serrations.

Modern Carcharodon

5) At a bonebed approximating the mio-pliocene boundary (5.33 Ma), there is a large sample of Carcharodon carcharias teeth with larger serrations (but still appear slightly smaller than extant C. carcharias)

6) At an early-middle Pliocene bonebed dated at 4.5-3.5 Ma, there is a very large sample of Carcharodon carcharias teeth, similar to the above

7) At an early-middle Pliocene locality dated at 5.33-2.5 Ma, there is a sample of Carcharodon carcharias that are nearly identical to modern Carcharodon in terms of their serration size.

That's how it breaks down in the Purisima Formation. Some of this has recently been published.

Bobby

Edited October 21, 2011 by Boesse

[wRick]

Here's a link to a post I did a while back about a Mako that has some ridges on it that seem like the beginnings of serrations: http://www.thefossil...__1#entry158626

It doesn't look like other Mako to GW transitionals I've seen, so it may be just a minor pathology, but it's still an interesting tooth, to me at least .