Megalodon

[elosha11]

Ok, this is kind of exciting. Here's the link to the article of the Denmark fossil centra and associated tooth (16 cm length 12 cm wide) 2dgf.dk/xpdf/bull32-01-02-1-32.pdf. GREAT read by the way. If it's not posted on WoA yet, it should be noted. It's probably documenting the officially largest Meg centra ever discovered, pending publication of Klaus' skeleton.

On page 8 of the Denmark study, it shows a picture of the largest centra, which measures 23 cms in diameter. Now, go the WoA page 1 on Klaus discovery at theworldofanimals.proboards.com/thread/208/carcharocles-megalodon-skeleton-peru and look at the second and third pictures the centra that Grey posted. (Unfortunately, it's probably a broken part of the skeleton after the Dakar Rally. I posted similar pictures of the broken portion of the skeleton further down the same page). Now compare the Denmark and Peruvian fossils. They are virtually the same structure. It further solidifies the proof in my mind that Klaus has discovered a very large fossil Megalodon. But more importantly to this thread, it appears that their growth rings well exceed thirty. It's hard to tell for sure, but just eyeballing it makes me think it's a much larger number than 30, probably over 50. Would need close examination to tell for sure, but I think it's quite likely that these very large specimens were way over thirty years old at time of death.

[Grey]

I would not try to count the rings on these centra from the photos, especially since the great white shark age has been totally revised recently and that Ehret thesis is older than this new discovery. But personnally, I'd not be surprised that C. megalodon could live very old, in excess of 50 years and up to 100 years, like most very large animals. Also, maybe megalodon potential maximum age changed through its existence, just like the body size itself.

I've found here two papers not only about Megalodon but mainly, these are quite recent and seem interesting. Only, even google translate does not work well with it and I was just unable to get something from it.

www.minerofil.hu/lelohely_pdf/2013_2.pdf
www.minerofil.hu/lelohely_pdf/2013_5.pdf

Maybe another European member here could understand something ?

[Grey]

A new University of Florida study dismisses claims that megalodon is still alive by determining a date of extinction for the largest predatory shark to ever live. news.ufl.edu/archive/2014/10/uf-study-megalodon-shark-became-extinct-26-million-years-ago.html Researchers from UF and the University of Zurich hope the study appearing online today in the journal PLOS ONE showing the species became extinct 2.6 million years ago will clarify public confusion. "Megalodon shark became extinct 2.6 million years ago"


When Did Carcharocles megalodon Become Extinct? A New Analysis of the Fossil Record


Carcharocles megalodon (“Megalodon”) is the largest shark that ever lived. Based on its distribution, dental morphology, and associated fauna, it has been suggested that this species was a cosmopolitan apex predator that fed on marine mammals from the middle Miocene to the Pliocene (15.9–2.6 Ma). Prevailing theory suggests that the extinction of apex predators affects ecosystem dynamics. Accordingly, knowing the time of extinction of C. megalodon is a fundamental step towards understanding the effects of such an event in ancient communities. However, the time of extinction of this important species has never been quantitatively assessed. Here, we synthesize the most recent records of C. megalodon from the literature and scientific collections and infer the date of its extinction by making a novel use of the Optimal Linear Estimation (OLE) model. Our results suggest that C. megalodon went extinct around 2.6 Ma. Furthermore, when contrasting our results with known ecological and macroevolutionary trends in marine mammals, it became evident that the modern composition and function of modern gigantic filter-feeding whales was established after the extinction of C. megalodon. Consequently, the study of the time of extinction of C. megalodon provides the basis to improve our understanding of the responses of marine species to the removal of apex predators, presenting a deep-time perspective for the conservation of modern ecosystems.

www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0111086



UF study: Megalodon shark became extinct 2.6 million years ago

GAINESVILLE, Fla. --- A new University of Florida study dismisses claims that megalodon is still alive by determining a date of extinction for the largest predatory shark to ever live.

Researchers from UF and the University of Zurich hope the study appearing online today in the journal PLOS ONE showing the species became extinct 2.6 million years ago will clarify public confusion. The study may also one day help scientists better understand the potential widespread effects of losing the planet’s top predators, said lead author Catalina Pimiento.

“I was drawn to the study of Carcharocles megalodon’s extinction because it is fundamental to know when species became extinct to then begin to understand the causes and consequences of such an event,” said Pimiento, a doctoral candidate at the Florida Museum of Natural History on the UF campus. “I also think people who are interested in this animal deserve to know what the scientific evidence shows, especially following Discovery Channel specials that implied megalodon may still be alive.”

The study represents the first phase of Pimiento’s ongoing reconstruction of megalodon’s extinction. As modern top predators, especially large sharks, are significantly declining worldwide due to the current biodiversity crisis, Pimiento said this study serves as the basis to better understand the consequences of these changes.

“When you remove large sharks, then small sharks are very abundant and they consume more of the invertebrates that we humans eat,” Pimiento said. “Recent estimations show that large-bodied, shallow-water species of sharks are at greatest risk among marine animals, and the overall risk of shark extinction is substantially higher than for most other vertebrates.”

Pimiento plans to further investigate possible correlations between changes in megalodon’s distribution and the evolutionary trends of marine mammals, such as whales and other sharks.

“When we calculated the time of megalodon’s extinction, we noticed that the modern function and gigantic sizes of filter feeder whales became established around that time,” Pimiento said. “Future research will investigate if megalodon’s extinction played a part in the evolution of these new classes of whales.”

The slowly unraveling details of megalodon’s extinction and various aspects of its natural history have consumed Pimiento’s research for the past six years, including ongoing analysis of megalodon’s body size and a 2010 PLOS ONE study that proposed Panama served as a nursery habitat for the species.

For the new study, researchers used databases and scientific literature of the most recent megalodon records and calculated the extinction using a novel mathematical model proven reliable in recent experimental testing by study co-author Christopher F. Clements with the Institute of Evolutionary Biology and Environmental Studies at the University of Zurich.

Vertebrate paleontologist Jorge Velez-Juarbe with the Natural History Museum of Los Angeles County said the study will not only serve as a key reference for debunking the myth that megalodon still exists, but its novel methods will influence the future of scientific research of extinct animals and plants.

“The methodology that the authors used had only been previously employed to determine extinction dates in historical times, such as to estimate the extinction date of the dodo bird,” Velez-Juarbe said. “In this work, scientists applied that same methodology to determine the extinction of an organism millions of years ago, instead of hundreds. It’s a new tool that paleo biologists didn't have, or rather had not thought of using before.”

news.ufl.edu/archive/2014/10/uf-study-megalodon-shark-became-extinct-26-million-years-ago.html



‘Megajaws’ kept blue whale small

SCIENTISTS have pinpointed the event that allowed the world’s biggest living creature to emerge — the demise of the world’s biggest ever shark.

The bus-sized “Carcharocles megalodon”, an 18-metre behemoth that feasted on marine mammals, is one of the most celebrated monsters of the deep. About four times as big as a great white, it evolved around 15 million years ago.

Scores of fossils and toothy reconstructions make megalodon a museum favourite. But despite its popularity and widespread fossil record, little has been known about its extinction.

Now an analysis of 42 of the most recent fossils has found the monster disappeared 2.6 million years ago — just before the filter-feeding baleen whales became giants.

The finding, and the fact that fossils of baleen whales are often found with megalodon teeth, suggests that the monster’s diet included the ancestors of humpbacks, southern rights and even blue whales, considered the heaviest creature ever.

Announcing the finding this morning in the journal PLOS ONE, the team says more research is needed to be sure that megalodon ate baleen whales. But it was only after megalodon’s extinction that baleen whales reached their “modern gigantic sizes”, the paper says.

Lead author Catalina Pimiento, of the University of Florida, said it was not clear what had killed off megalodon. “That will be the subject of my next project,” she said.

www.theaustralian.com.au/higher-education/megajaws-kept-blue-whale-small/story-e6frgcjx-1227098988961



Giant Megalodon Shark disappeared 2.6 million years ago


NEW YORK: The debate over the existence of Megalodon recently sparked up again. However, a new study has established that the giant shark was actually extinct some 2.6 million years ago.

The researchers started the study on the fossils of the gigantic shark. The ancient shark which used to be almost 60 ft in size was a fierce marine predator. The sharks were the largest ever to live mostly relied on the diet of Ocean mammals like whales and dolphins. The researchers said that the fossils are aged almost 2.6 million years, and the date might fall anytime between Pliocene and Pleistocene Epochs. Scientists added that this was exactly the time when the Ocean mammals also started growing in numbers in the earth’s ocean. The increase in population of the blue whale and the dolphins was only possible if the giant Megalodon Shark became extinct.
Scientists have estimated the time of the extinction. However, they are still without any clue about the reason of extinction. The 18 meters long giant shark was not extinct in a day. There would have been a strong reason for the extinction. It could be a geological change or climate change or any biological problem with the species. But as of now, they have only came closer to fact that the myth that Megalodon still exists is actually a myth. They disappeared from the earth some 2.6 million years ago. The researchers are still continuing their study, and the reason might get unveiled pretty soon as well.

www.theeasterntribune.com/story/8024/giant-megalodon-shark-disappeared-2-6-million-years-ago/#sthash.AbaEZUDs.dpbs

[Grey]

8 x 10 Foot Meg Jaw

This is both the largest and highest quality reproduction megalodon jaw available in the world. Measures appx 7.5 feet tall x 9.5 feet wide and is made from fiberglass with all teeth being VERY exact casts of real fossil teeth. Largest teeth measure appx 6 3/4" in length and the placements are scientifically accurate. We have sold this model to several different museums/aquaria and from experience can safely say that this is a real money maker for photo ops and increased crowds. We've even sold jaws for twice the price of this model that paid for themselves in one Summer by photographic revenue alone!!!

All jaws are custom built and take appx 3-4 months to complete. Eye bolts can be installed as needed for hanging or can be made into floor mounts. Very solidly built however these are light enough to be moved by two people. Please call for price and further information.



megalodonteeth.com/reconstructed-shark-jaws/8-x-10-foot-meg-jaw

[Grey]

Earth Sciences Palaeo Discussion Group - Dr Catalina Pimiento - The Smithsonian Institution, USA - The extinction of the largest marine top predator that ever lived

Abstract

The mechanisms of extinction of Carcharocles megalodon (Megalodon) are unknown. Based on the widespread distribution of its fossil teeth, and their extreme size and sharp edges, it has been suggested that C. megalodon was a cosmopolitan species, and one of the largest marine top predators that ever lived. As a top predatory shark, C. megalodon most likely played a key role in structuring the world's marine ecosystems. Consequently, its extinction potentially affected food webs and impacted ecosystems’ structure and function.

My research uses quantitative methods to investigate the extinction mechanisms of this important apex predator, and has estimated the body size of individuals from a large sample across regions and time periods in order to test the hypothesis of body size increase over time as a cause of its extinction. I found that C. megalodon did not increase in size over time, and hence found no support for this hypothesis. Finally, I am using all the records of C. megalodon to assess changes in its geographic distribution throughout its entire duration. This approach is being used to identify C. megalodon’s pathway to extinction.

Since marine apex predators are significantly declining in all the oceans of the world, studies to determine their extinction mechanisms have long been an interest of modern ecology. Despite major shifts in baseline abundances, no species of modern marine apex predator has become extinct. Consequently, my research on the extinction of the largest marine apex predator of the world can potentially provide a deep-time perspective on the conservation of modern predatory sharks.

www.bristol.ac.uk/earthsciences/events/2015/earth-sciences---palaeo-discussion-group---dr-catalina-pimiento.html

[Grey]

Dental lessons from past to present: ultrastructure and composition of teeth from plesiosaurs, dinosaurs, extinct and recent sharks†
A. L¨
ubke,a J. Enax,a K. Loza,a O. Prymak,a P. Gaengler,b H.-O. Fabritius,c D. Raabec and M. Epple*a

Teeth represent the hardest tissue in vertebrates and appear very early in their evolution as an ancestral character of the Eugnathostomata (true jawed vertebrates). In recent vertebrates, two strategies to form and mineralize the outermost functional layer have persisted. In cartilaginous fish, the enameloid is of ectomesenchymal origin with fluoroapatite as the mineral phase. All other groups form enamel of ectodermal origin using hydroxyapatite as the mineral phase. The high abundance of teeth in the fossil record is ideal to compare structure and composition of teeth from extinct groups with those of their recent successors to elucidate possible evolutionary changes. Here, we studied the chemical composition and the microstructure of the teeth of six extinct shark species, two species of extinct marine reptiles and two dinosaur species using high-resolution chemical and microscopic methods. Although many of the ultrastructural features of fossilized teeth are similar to recent ones (especially for sharks where the ultrastructure basically did not change over millions of years), we found surprising differences in chemical composition. The tooth mineral of all extinct sharks was fluoroapatite in both dentin and enameloid, in sharp contrast to recent sharks where fluoroapatite is only found in enameloid. Unlike extinct sharks, recent sharks use hydroxyapatite as mineral in dentin. Most notably and hitherto unknown, all dinosaur and extinct marine reptile teeth contained fluoroapatite as mineral in dentin and enamel. Our results indicate a drastic change in the tooth mineralization strategy especially for terrestrial vertebrates that must have set in after the cretaceous period. Possibly, this is related to hitherto unconsidered environmental changes that caused unfavourable conditions for the use of fluoroapatite as tooth mineral.



app.box.com/s/cfqecz4xz8oljjdizn42ara9ch7t839r


Megalodon Had Super-Power Teeth with Built-In Toothpaste

The largest known shark known to have lived, Megalodon, had teeth that were unlike those of any living animal, according to new research.

Large and powerful Megalodon, which grew up to 66 feet long, flashed teeth that were heavily comprised of fluoride, the new study determined. Modern sharks only have fluoride on the surface, or enamel, of their teeth. The findings are published in the journal RSC Advances.

“You might say that they also used ‘built-in toothpaste,’” senior author Matthias Epple, a professor at the University of Duisburg-Essen’s Institute of Inorganic Chemistry, told Discovery News.

“The ‘built-in toothpaste’ refers to the fluoride content,” he said, adding that Megalodon never suffered from cavities.

This, however, was primarily because the enormous shark had a “revolving jaw” that regularly replaced any teeth that went missing, maybe left behind in prey. Today’s great whites and other sharks benefit from such a replacement system too.

Megalodon teeth were almost 8 inches long, making them much larger than those of any living shark. Now extinct, Megalodon is thought to have terrorized ocean dwellers from around 16 to 2 million years ago.

For the study, Epple and his colleagues compared Megalodon teeth with teeth from five other extinct shark species, three living sharks (great white, tiger and mako), as well as teeth from two extinct marine reptiles and two dinosaurs: Spinosaurus marocannus (“Spine Lizard”) and Carcharodontosaurus saharicus. Both of the dinosaurs were large carnivores.

The researchers focused on the chemical composition and microstructure of the teeth from these animals and determined that the now-extinct sharks and dinosaurs had fluoride on and within both the surface and interiors (dentin) of their teeth. This unique chemical composition occurred in these animals and related species for more than 100 million years.

A few million years ago, sharks evolved teeth that only had fluorapatite (the mineral associated with the compound fluoride) on the surface. The dentin mineral is now primarily hydroxyapatite, which comprises about 96 percent of human tooth enamel.

Why the switch happened remains a mystery, but Epple and his team suspect that fluorapatite must have been more common in prehistoric times than it is today. He explained that now “fluoride is not very common in seawater, (so) it is difficult for animals to collect fluoride, especially for a revolving jaw in sharks where the teeth are replaced every few weeks or months.”

According to a University of California at Santa Barbara fact sheet, “Fluorapatite is more resistant to decay than is hydroxyapatite.” Epple also said that “fluoroapatite as a mineral is slightly harder than hydroxyapatite.”

That could be that Megalodon and the other prehistoric animals had sturdier teeth than any living creature today.

On the other hand, Epple said that fluorapatite releases a damaging acid -- hydrofluoric acid -- on contact with acidic fruits and certain other edibles, like meat, which are found on land.

He does not think dinosaurs suffered from tooth decay much, though.

“They used fluoride in teeth for several millions of years without apparent problems,” he said, adding that the carnivorous dinosaurs that he and his colleagues studied probably rarely, if ever, ate fruit.

Diet also helps to explain why humans did not evolve continuously replacing teeth, like those of sharks.

Barry Berkovitz of King’s College London’s School of Biomedical Sciences, explained, “Continuous tooth replacement is particularly inefficient in mammals where teeth bite together to masticate food. They have evolved different strategies to cope with having only two sets of teeth during their lives.”

He added, “In humans, the ultimate solution is to get a third set from the dentist!”


news.discovery.com/animals/sharks/megalodon-had-super-power-teeth-with-built-in-toothpaste-150717.htm

[Grey]

[Grey]

Record of Carcharocles megalodon in the Eastern Guadalquivir Basin (Upper Miocene, South Spain)
Registro de Carcharocles megalodon en el sector oriental de la Cuenca del Guadalquivir (Mioceno superior, Sur de España)

M. Reolid, J.M. Molina
Departamento de Geología, Universidad de Jaén, Campus Las Lagunillas sn, 23071 Jaén, Spain.

ABSTRACT
Tortonian diatomites of the San Felix Quarry (Porcuna), in the Eastern Guadalquivir Basin, have given isolated marine vertebrate remains that include a large shark tooth (123.96 mm from apex to the baseline of the root). The large size of the crown height (92.2 mm), the triangular shape, the broad serrated crown, the convex lingual face and flat labial face, and the robust, thick angled root determine that this specimen corresponds to Carcharocles megalodon. The symmetry with low slant shows it to be an upper anterior tooth. The total length estimated from the tooth crown height is calculated by means of different methods, and comparison is made with Carcharodon carcharias. The final inferred total length of around 11 m classifies this specimen in the upper size range of the known C. megalodon specimens.
The palaeogeography of the Guadalquivir Basin close to the North Betic Strait, which connected the Atlantic Ocean to the Mediterranean Sea, favoured the interaction of the cold nutrient-rich Atlantic waters with warmer Mediterranean waters. The presence of diatomites indicates potential upwelling currents in this context, as well as high productivity favouring the presence of large vertebrates such as mysticetid whales, pinnipeds and small sharks (Isurus). These large vertebrates recorded in the Eastern Guadalquivir Basin were potential prey of C. megalodon.

estudiosgeol.revistas.csic.es/index.php/estudiosgeol/article/view/926/1024

[Grey]

PHYLOGENETIC PREDICTIVE BODY SIZE ESTIMATES OF EXTINCT
SHARKS

PEART, Samantha, North Carolina State University, Raleigh, NC, United States of
America, 27695; GATES, Terry A., North Carolina Museum of Natural Sciences,
Raleigh, NC, United States of America; CAMPIONE, Nicolas E., Uppsala University,
Uppsala, Sweden
Obtaining biological information, such as body size, for extinct sharks is notoriously
difficult given that so few anatomical structures preserve in the fossil record. Teeth are by
far the most common, but their utility as a body size predictor is potentially limited by
their ecomorphological variability compared to other structures such as vertebrae.
However, their abundance throughout the geologic record and their seeming diagnostic
importance relative to vertebrae demonstrates their paramount utility for understanding
macroevolutionary patterns of body size in extinct aquatic species. Prior attempts to
estimate body size in extinct sharks, such as Carcharocles megalodon, applied simple
length:width ratios based on a single extant model, Carcharodon carcharias.
Accordingly, a broad, interspecific extant model investigated within a phylogenetic
context is lacking. Our approach utilized a combined molecular-morphological
topological framework within the predictive models in BayesTraits to estimate the body
length of several fossil taxa using a phylogenetic generalized least squares model of 15
modern shark species (nine carcharhiniforms, five lamniforms, and Hexanchus grisseus
as an outgroup). Fossil shark taxa estimated in our study include the Cretaceous species
Cretalamna appendiculata, Cretoxyrhina mantelli, Squalicorax sp., and
Scapanorhynchus sp., the Eocene-aged Carcharodon auriculata, and the Mio-Pliocene
taxa Hexanchus sp., Isurus hastalis, and C. megalodon. An initial multiple regression
model between total body length and five linear measurements on teeth throughout the
jaws of only modern species revealed strong correlations with mean R2
values of 0.966
(mid-dentary teeth have highest correlation R2
of 0.98) and a moderate mean lambda
(phylogenetic signal, 0.7). Fossil taxa were then included in the regression analysis using
the phylogenetically informed model saved from the previous run in order to inform the
body size predictions. Our results predict a body length of 13 m for C. megalodon, using
a 132 mm dorsoventral length mid-maxillary tooth, which is not the largest specimen documented from the fossil record. This estimate is consistent with early size predictions
for the species, yet much smaller than recent assessments hypothesizing lengths >16 m.
Another large-toothed shark I. hastalis is predicted at 5 m from the same tooth position.
Our approach supports the use of shark teeth as size estimators, provided that estimates
are generated within a phylogenetic context.

[elosha11]

^Interesting analysis but definitely seems a minority view, as to size estimation. For instance it appears the may are trying to predict Isurus hastalis at only 5 meters maximum, but most scientists commonly believe it was larger than a great white. If Klaus Honninger can be credited, he has stated he found I. hastalis vertebral skeletons that exceeded 6 meters and he has provided pictures of entire juvenile I. hastalis skeletons, as well as adult ones destroyed by the Dakar. And suggesting C. megalodon's maximum may have only been 13-16 meters is a minority view.

[Grey]

Mainly but not only focused on megalodon :

revistes.ub.edu/index.php/GEOACTA/article/viewFile/GeologicaActa2015.13.3.1/17318

[Grey]

web.archive.org/web/20120306025901/http://webapp2.wright.edu/web1/regionalsummit/2009/08/01/shark-tales/

[Grey]

www.fossilmegasharkteeth.com/megalodon/

[Grey]

This model from the Calvert Marine Museum appears to be the updated version of the body shape based on B.K. recommendations, it looks very much like his early draft.



If true, this the most up to date reconstruction of the critter.

www.calvertmarinemuseum.com/334/Vertebrate-Fossils

[Grey]

Speed of giant prehistoric shark revealed

www.zsl.org/science/news/speed-of-giant-prehistoric-shark-revealed


rsbl.royalsocietypublishing.org/content/11/12/20150781