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Post by elosha11 on Sept 14, 2022 4:20:57 GMT 5
Yup I know of those large-sized whales. There were 10 m plus cetaceans back then but they were not the most numerous and not quite yet at the scale of the gigantic Plio-Pleistocene post-meg baleen whales. With the possibility of Megalodon being primarily a predator of top predators (Kast 2022), maybe those whales were not primary targets for the big fish. I actually think the evidence seems to be more that Megalodon ate practically anything it wanted, big or small, predator or baleen whale. We've got numerous pieces of fossil evidence that it fed on pretty large cetaceans, judging by the bite marks on large vertebral centra and even fossil sperm whale teeth. Those bones certainly seem to depict some baleen or physeter whales that would be 12 m and perhaps significantly larger. Of course still no way to exactly tell if it was all predation, all scavenging, or as most likely, some mixture of the two. And then of course we have what appears to be Megalodon bite marks on significantly smaller baleen whales, medium sized dolphins, and medium sized predatory whales/sperm whales. But the mixture is so diverse and widespread, I have a hard time figuring out why anyone could say Megalodon was specialized in on one particular target. In general terms of the species history, it seemed to be targeting practically everything. That's why I always found it puzzling that papers would come out stating things like Megalodon may have been a small prey predator merely because they happen to find a few relatively small animals with Megalodon bite marks, and ignoring much bigger fossil predations. As you both probably know, Cooper/Pimiento's latest 2022 paper actually seems to indicate that Megalodons would be more calorically advantaged by pursuing medium-to-large size prey rather than really small ones. Which makes perfect sense for such a massive predator. It really would be interesting to get further research on Livyatan's ecology as well. That trophic study does sound interesting, but as theropod suggests, its findings are not definitive. |
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Post by Life on Sept 23, 2022 22:41:42 GMT 5
SVP abstract. It concludes that the isotopic levels do not suggest the Livyatan specimen was completely macrophagous, meaning always consuming large animals. This does possibly suggest that this specimen, at least, was feeding at a lower trophic level than the Megalodons tested in the recent study. I do note that this seems to be determining isotopic levels based on oxygen and carbon composition, whereas the Megalodon study was based on isotopic levels produced by nitrogen. I'm not sure if it makes a difference.  I think we discussed this some years ago, but there still seems to be nothing new on the subject, and no clarification about the results. There are various confounding factors in isotopic analysis, many of which are at play here. Starting with the most apparent; neither Oxygen nor Carbon isotopes are good trophic indicators (Soto et al. 2013, Kelly 2000). Latitude and temperature plays a huge role, and this is acknowledged in the abstract, while conclusions about trophic ecology seem much more doubtful–only logical considering they already found that the individual fed at high latitudes, which would have the predicted effect of lowering oxygen and carbon ratios. Without the actual data (and appropriate baselines) the options for comparison here are limited. We could probably compare Livyatan to O. orca and other odontocetes from the same (southern) latitude, but we don’t know what was used as a baseline in the research leading to that abstract, neither do we know the actual figures for the isotope ratios that they found. We could also maybe compare them to sharks from the same locality, but of course only if we had data for the same isotopes for both. So what isotopes are used matters a lot, consider for example the contradicting results of two recent studies on O. megalodon trophic ecology; one used Nitrogen isotopes and found extremely high trophic position (Kast et al. 2022), the other used zinc isotopes and found feeding at a trophic level similar to coexisting C. carcharias (McCormack et al. 2022). For comparing two taxa, one should compare the same isotopes (and also the same provenance, of course), not different isotopes that are known to be affected differently by the provenance of the samples. That would be less than ideal if there were detailed, repeated studies showing an overarching consensus (but based on different methods), with one taxon only analyzed once, based on a single time, and only based on an abstract giving very little details, it’s clearly not a sound comparison. Another important thing to keep in mind is what "trophic level" actually means. Consider that a large rorqual (feeding on fish or krill) is on the same or a lower lower trophic level than a dolphin or pinniped (feeding on fish or squid). That is important in interpreting several recent isotopic analyses in the context of other data. For example the recent study (McCormack et al. 2022) that found O. megalodon feeding at a similar trophic level to C. carcharias; this does not mean it necessarily fed on the same (sized) prey, in fact it could have conceivably fed on mysticetes without having a higher trophic level than a C. carcharias feeding on pinnipeds.
I get the impression (from how frequently this gets posted in AvA topics, especially ones about O. megalodon) that trophic level gets conflated with how "formidable" a predator or its prey is perceived to be, but, counterintuitively, this is not a correct interpretation. I think we would all agree that preying on a humpback whale is a lot more impressive than preying on a sea lion, but the trophic level is the same (and the trophic level from feeding on a Rorqual more specialized in krill than fish might be even lower). Hublin, J.-J., Eagle, R.A. and Tütken, T. 2022. Trophic position of Otodus megalodon and great white sharks through time revealed by zinc isotopes. Nature Communications 13 (1): 2980.
Kast, E.R., Griffiths, M.L., Kim, S.L., Rao, Z.C., Shimada, K., Becker, M.A., Maisch, H.M., Eagle, R.A., Clarke, C.A., Neumann, A.N., Karnes, M.E., Lüdecke, T., Leichliter, J.N., Martínez-García, A., Akhtar, A.A., Wang, X.T., Haug, G.H. and Sigman, D.M. 2022. Cenozoic megatooth sharks occupied extremely high trophic positions. Science Advances.
Kelly, J.F. 2000. Stable isotopes of carbon and nitrogen in the study of avian and mammalian trophic ecology. Canadian journal of zoology 78 (1): 1–27.
McCormack, J., Griffiths, M.L., Kim, S.L., Shimada, K., Karnes, M., Maisch, H., Pederzani, S., Bourgon, N., Jaouen, K., Becker, M.A., Jöns, N., Sisma-Ventura, G., Straube, N., Pollerspöck, J., Hublin, J.-J., Eagle, R.A. and Tütken, T. 2022. Trophic position of Otodus megalodon and great white sharks through time revealed by zinc isotopes. Nature Communications 13 (1): 2980.
Soto, D.X., Wassenaar, L.I. and Hobson, K.A. 2013. Stable hydrogen and oxygen isotopes in aquatic food webs are tracers of diet and provenance. Functional Ecology 27 (2): 535–543.
Well-reasoned and I agree with your assertion that "what isotopes are used matters a lot" to draw meaningful inferences about dietary preferences and trophic levels of various animals. Both Calcium isotopes (Martin et al., 2015) and Nitrogen isotopes (Kast et al., 2022) have established that Otodus chubutensis followed by Otodus megalodon fed on a higher trophic level than Isurus hastalis followed by Carcharodon carcharias.
Zinc isotopes are also instructive about dietary preferences of various animals (Jaouen et al., 2016), but nitrogen isotopes are useful for unmasking trophic level(s) of animals (Jaouen et al., 2016; Kast et al., 2022), and WE should expect to see a negative correlation between nitrogen isotopes and zinc isotopes in food webs (Jaouen et al., 2016). This explains contradiction between inferences that could be drawn from nitrogen isotopes and zinc isotopes of Otodus megalodon and Carcharodon carcharias in two different but recent studies [(Kast et al., 2022) vs (McCormack et al., 2022)].
Is it possible to address said contradiction? OF-COURSE. WE consider findings of all isotopes in our assessment. Findings of Zinc isotopes are technically valid but Nitrogen isotopes have disclosed HOW capable genus Otodus (i.e., same shark evolving through time and space) was while contending with other macropredators through time and space. Inferences in (McCormack et al., 2022) need a REVISIT in view of findings of both Calcium isotopes and Nitrogen isotopes in fact. Competition hypothesis can be challenged for instance.
There is fossil record of trophic interactions between genus Otodus and different dolphins including macroraptorial squalodontids (Aguilera & de Aguilera, 2004; Godfrey et al., 2018). There is also fossil record of trophic interactions between genus Otodus and macroraptorial physeteroids (Godfrey et al., 2021); additional examples in private hands. But frequency of these antagonistic interactions was unclear. But now, Nitrogen isotopes provide a whole new perspective in relation.
To put it mildly: genus Otodus was able to attack and consume other large-bodied macropredators on a frequent basis. Odontocetes and OTHER sharks were FAIR GAME.
There is evidence of emergence of large-bodied macropredatory dolphins in the Oligocene epoch (Boessenecker et al., 2020), but findings of Nitrogen isotopes coupled with the fossil record of dolphins, can be used to challenge and debunk the hypothesis that macropredatory dolphins could handle genus Otodus in trophic interactions on a frequent basis, and have a hand in its extinction in support of similar contention in (Boessenecker et al., 2019). Orcinus citoniensis is a significant discovery from evolutionary standpoint but a JOKE in comparison to numerous macropredators that existed in the Miocene epoch and earlier times; O. citoniensis consumed small fishes in large part and it looks like genus Orcinus became larger and managed to occupy higher trophic levels in the Pliestocene epoch in the absence of genus Otodus (Citron et al., 2022). CORRECT assumption is that genus Orcinus have slowly but surely filled the ecological void of genus Otodus in marine environments around the world in the Pliestocene epoch. This debate is virtually settled.
Even macroraptorial physeteriods could not affect genus Otodus (Boessenecker et al., 2019). Zinc isotopes indicate that both Otodus megalodon and Carcharodon carcharias consumed baleen whales. Now what can WE deduce from this inference on its own? Not much. Nitrogen isotopes are simply setting the record straight when it comes to evaluating predatory prowess of genus Otodus through time. These findings will help DEBUNK some of the premature/ill-informed conclusions of the Max Hawthorne variety found in several sources including in Renz (2002) and Pimiento et al (2016). Shark experts were supposed to set the record straight but it looks like cetacean experts are setting the record straight. Ecological reconstruction of genus Otodus is an ambitious undertaking and not possible in a short span of time; this theme demands advances in cetacean and environmental sciences in tandem. There is a need to examine biodiversity trends and shifts in distribution patterns. There is also a need to figure out where genus Otodus was present and where it could not function. Reliable dating of the fossil record is necessary (Boessenecker et al., 2019). GOOD SCIENCE should take precedence over jumping to premature/ill-informed conclusions on the whole.
Climatic shifts and/or environmental upheavals posit a significant threat to numerous life-forms around the world. Multiple studies have established that there were numerous environmental upheavals in the Late Miocene timeline as well as in the Pliocene epoch. Some animals have modest dietary requirements and have managed to subsist in limited geographical spaces and/or in small numbers when things got rough. Apex consumers can be much more vulnerable in comparison. Apex consumers are known to produce significant top-down effects on other species but range fragmentation as well as a drop in biodiversity due to climatic shifts and/or environmental upheavals can be detrimental to them. In the present, genus Orcinus have the upper hand over macropredatory sharks in trophic positions but climatic shifts (and cooling trend) of earlier times have facilitated this turnover (Citron et al., 2022).
References Aguilera, O. R. A. N. G. E. L., & de Aguilera, D. R. (2004). Giant-toothed white sharks and wide-toothed mako (Lamnidae) from the Venezuela Neogene: their role in the Caribbean, shallow-water fish assemblage. Caribbean Journal of Science, 40(3), 368-382.
Boessenecker, R. W., Ehret, D. J., Long, D. J., Churchill, M., Martin, E., & Boessenecker, S. J. (2019). The Early Pliocene extinction of the mega-toothed shark Otodus megalodon: a view from the eastern North Pacific. PeerJ, 7, e6088.
Boessenecker, R. W., Churchill, M., Buchholtz, E. A., Beatty, B. L., & Geisler, J. H. (2020). Convergent evolution of swimming adaptations in modern whales revealed by a large macrophagous dolphin from the Oligocene of South Carolina. Current Biology, 30(16), 3267-3273.
Citron, S., Geisler, J. H., Collareta, A., & Bianucci, G. (2022). Systematics, phylogeny and feeding behavior of the oldest killer whale: a reappraisal of Orcinus citoniensis (Capellini, 1883) from the Pliocene of Tuscany (Italy). Bollettino della Società Paleontologica Italiana, 61(2), 168.
Godfrey, S. J., Ellwood, M., Groff, S., & Verdin, M. S. (2018). Carcharocles-bitten odontocete caudal vertebrae from the Coastal Eastern United States. Acta Palaeontologica Polonica, 63(3). Godfrey, S. J., Nance, J. R., & Riker, N. L. (2021). Otodus-bitten sperm whale tooth from the Neogene of the Coastal Eastern United States. Acta Palaeontologica Polonica, 66(3), 599-603.
Jaouen, K., Szpak, P., & Richards, M. P. (2016). Zinc isotope ratios as indicators of diet and trophic level in arctic marine mammals. PLoS One, 11(3), e0152299. Renz, M. (2002). Megalodon: hunting the hunter. Paleo Press.
Martin, J. E., Tacail, T., Adnet, S., Girard, C., & Balter, V. (2015). Calcium isotopes reveal the trophic position of extant and fossil elasmobranchs. Chemical Geology, 415, 118-125. McCormack, J., Griffiths, M. L., Kim, S. L., Shimada, K., Karnes, M., Maisch, H., ... & Tütken, T. (2022). Trophic position of Otodus megalodon and great white sharks through time revealed by zinc isotopes. Nature Communications, 13(1), 1-10. Pimiento, C., MacFadden, B. J., Clements, C. F., Varela, S., Jaramillo, C., Velez‐Juarbe, J., & Silliman, B. R. (2016). Geographical distribution patterns of Carcharocles megalodon over time reveal clues about extinction mechanisms. Journal of Biogeography, 43(8), 1645-1655.
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Post by jhg on Oct 4, 2022 0:01:31 GMT 5
I used to think Megalodon would win and that was before I knew Livyatan.
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Post by elosha11 on Oct 4, 2022 15:28:51 GMT 5
I used to think Megalodon would win and that was before I knew Livyatan. It's definitely fun to think about. Clash of titans and maybe one of the most epic battles of all time. Do you have specific reasons you favor Livyatan? Based on a lot of the evidence including the most recent, I favor Megalodon but I would never fault anyone for going with one or the other. |
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Post by jhg on Oct 4, 2022 20:40:18 GMT 5
I think it’s smarter, not behind in the bite force and size, and has a big head to maybe ram.
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Post by Grey on Oct 5, 2022 2:30:07 GMT 5
Smartness is relative, a false killer whale is smarter than GWS yet it does not sem to outclass it in trophic dominance.
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Post by Life on Oct 5, 2022 5:27:22 GMT 5
I think it’s smarter, not behind in the bite force and size, and has a big head to maybe ram. Being smarter does not guarantee advantage in trophic interaction(s). The animal should have good senses on the other hand. For example: Great white shark ( Carcharodon carcharias) have good senses and understands where to bite a particular animal. It is not as simple as bite anywhere and retreat. WE do not know about the bite force of Livyatan melvillei. Large-bodied sharks can be physically very strong and capable of ramming prey. Scientists have noticed terrible injuries on vertebrae of some whales and suspect that a Megalodon could produce such blunt forces and inflicted these injuries. |
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Post by elosha11 on Oct 5, 2022 18:04:01 GMT 5
At parity, I'd likely favor Megalodon given lamnids and other large sharks' relative predatory dominance over similar-sized cetaceans today. Only when the shark is massively outclassed in size with the orca do the tables really turn.
Our current knowledge, although obviously somewhat limited, does seem to indicate the shark was larger than has previously been indicated and that large adult sharks could be quite a bit larger than the holotype Livyatan and may have exceeded 20m. The whale holotype which is reasonably estimated at 15 to 16 m, but may have been smaller or a bit larger than that, with a total estimated range of 13 to 17.5 m.
The big unanswered (and perhaps unanswerable) question is how big could the sharks get and how big could the whale get. And when I speak about maximum size, I'm really talking about the ordinary level of maximum size, not some abnormal individual that may have been a giant and aberration even among its own species. In other words, a very large / maximum size that adult sharks and adult whales could reasonably be expected to reach on a relatively common basis if they lived long enough and had enough food sources.
This also doesn't address the issue of whether bull Livyatans lived in pods or least associated with other bulls or females. We tend to think the sperm whale is their closest relative, and bull sperm whales sometimes are solitary, sometimes loosely associated with other males, and sometimes join the females and calf pods, likely for mating and territorial purposes.
Obviously, a large group of Livyatans create a greater deterrent, and/or threat to a Megalodon than vice versa. Probably one of the reasons we see relatively few interactions between large sharks and false killer whales is because false killer whales are very large themselves, have a relatively formidable bite, and live in very large pods. But there does seem indications that large sharks will prey on them or at least attempt to prey upon them on occasion. This is a very loose analogy (albeit probably the best modern proximity available), but it may have been a similar situation with Megalodon and Livyatan.
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Post by Life on Oct 8, 2022 6:18:42 GMT 5
Ecological reconstruction of Livyatan-like forms is necessary to draw meaningful inferences. Unfortunately, WE are looking at a collection of erroneous claims and a patchy fossil record: 1. Piazza et al (2018) report two isolated teeth from the Gran Bajo del Gualicho Formation in Argentina; this formation corresponds to the (18 - 16 Ma) time interval according to Del-Río & Martínez (2021). These teeth are large in size but do NOT represent individuals comparable in size to the Livyatan melvillei holotype [not even close]. This is the earliest record of Livyatan-like forms, nevertheless.
2. Piazza et al (2018) also report an isolated tooth from the Bahía Inglesa Formation in Chile but I was unable to retrace this evidence independently. Piazza et al (2018) cite Gutstein et al. (2015) for this record who in turn cite Pyenson et al (2011) as the source but NO record of this particular paper is found on Google Scholar and otherwise. This is why it is important for authors to RECHECK THEIR SOURCES when writing an article. Errors like these can lead to development of BAD INFERENCES and/or misconceptions.
Piazza et al (2018) present INFLATED stratigraphic range for Livyatan-like forms. Now how many Wiki editors would notice the obvious? 3. Govender (2019) disclosed five isolated teeth from Hondeklip Bay in South Africa circa 5 Ma. Among these specimens, two isolated teeth are comparable in size to teeth of the L. melvillei holotype. This is the most recent record of Livyatan-like forms. 4. An isolated tooth was also reported from Beaumaris Bay in Australia circa 5 Ma. -----
POINTER: The aforementioned papers and records collectively suggest a strategic range of 18 - 5 Ma for Livyatan-like forms around the world. ----- Piazza et al (2018) particularly noted that Livyatan-like forms were restricted to the southern hemisphere. WE can look at the extant southern right whales ( Eubalaena australis) to address this mystery: "Because of the thick layer of blubber in their bodies, these whales do not cross the equator into the northern hemisphere as their bodies are unable to cope with the extreme heat." - Animalia-----
POINTER: Livyatan-like forms can be assumed to have a thick layer of blubber in their bodies. ----- Cetaceans use sound for communication, navigation and finding prey (Galatius et al., 2018). It shall be noted that odontocetes developed echolocation in the Oligocene epoch (Geisler et al., 2014; Pyenson et al., 2017; Serio et al., 2019).
Echolocating abilities of macro-raptorial sperm whales as a theme is LACKING in literature unfortunately. Galatius et al (2018) find Acrophyseter deinodon to be similar to the extant killer whales (Orcinus orca) in the context of echolocating abilities and helped identify some of its prey items such as Kogiidae, Pontoporiidae and Phocoenidae; this study is instructive for similar research on other macro-raptorial sperm whales.
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POINTER: Livyatan-like forms can be assumed to have echolocation.
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Social habits of macroraptorial sperm whales including Livyatan-like forms are virtually unknown (Collareta et al., 2021).
Livyatan-like forms might be intelligent and social on the level of the extant sperm whale (Physeter macrocephalus) but (Bianucci & Collareta, 2022) contend that P. macrocephalus exhibit contrasted patterns of sociability.
Livyatan-like forms were macroraptorial and might have behaved like the extant transient killer whales (Bigg's O. orca). But I am NOT sure about formation of large groups.
NOW THE QUESTION IS: Livyatan-like forms could challenge and compete with gigantic sharks? 1. NOT GLOBALLY but in the southern hemisphere.
2. The genus Otodus responded to GLOBAL RADIATION of macro-raptorial sperm whales by growing much bigger and stronger than ever before (Otodus chubutensis -> Otodus megalodon). Perez et al (2018) pointed out that this transition was complete circa 7 Ma. Benites-Palomino (2022) acknowledged this REALITY the way it should be. O. megalodon WAS THE ANSWER to the problem of L. melvillei in Peruvian waters.
What message does the footage convey? It takes a METAL to cut another METAL
WE are looking at a very complex and well-developed organism in genus Otodus. What if these sharks were willing to partake in "cooperative hunting" in their own style? AND?
Livyatan-like forms are noticed in Peruvian waters in the (10 - 8 Ma) time interval. But NO FURTHER RECORDS in this PARTICULAR REGION. Acrophyseter-like form is present on the other hand but it was mere snack; Benites-Palomino (2022) disclosed a predatory attack on the Acrophyseter-like form in fact.
Cooling trend should NOT be a problem; THICK BLUBBER was the SOLUTION. But I have following observations: 1. Gigantic mysticetes are noticed in Peruvian waters during the Miocene epoch (Bianucci & Collareta, 2022). These whales would be difficult to handle and/or capture but Livyatan-like forms conform to GRIP and TEAR prey processing strategy (Bianucci & Collareta, 2022), and should be up to the task with "cooperative hunting." RIGHT? But:
2. How the L. melvillei holotype DIED? Paleontologists found a skull but Where is the REST OF THE BODY? There is no proof of a Tornado passing over it, right?
Benites-Palomino (2022) disclosed signs of scavenging on the skull of L. melvillei from various sharks and inferred obligate scavenging event. But they also pointed out following:
"Modern sharks tend to focalize their scavenging efforts on regions of the cetacean body with a high concentration of dense lipids, such as the visceral blubber of the lower abdomen [1,70]. The bite marks on the physeteroid specimens here reported are congruent with this preference of sharks toward regions with high concentrations of fats. However, it is not possible to confirm that this was the sole region targeted as most of these findings correspond solely to isolated skulls without an articulated skeleton. Furthermore, a scenario in which Miocene sharks actively preyed on sperm whales, especially kogiids, is not dismissed, as some of the specimens here reported might have been directly preyed upon by sharks and posteriorly scavenged by other individuals."
Fossil records indicate ONE PARTICULAR MONSTER aiming for the RIB CAGE of large whales in TITANIC battles with them. Guess who.
Benites-Palomino (2022) also pointed out following:
"The findings reported herein testify to a consistent feeding pattern of Miocene sharks and the role of sperm whale carcasses as an important food source (figure 3), not only in the Pisco palaeo-area but possibly worldwide. These shark–physeteroid trophic interactions have no direct modern equivalents and indicate that, despite similarities at the community level, trophic roles in the oceans were much different just a few million years ago."
INDEED
Granted that Livyatan-like forms were present in South Africa and Australia circa 5 Ma but this might be a SHIFT in distribution pattern due to competitive pressure from genus Otodus.
But C. carcharias versus O. orca ?
NOPE Ever wonder why shortfin mako shark (Isurus oxyrinchus) and C. carcharias have similar dietary preferences and comparable trophic levels? C. carcharias is a branch-off from the Isurus line-up of sharks but it is more effective in keeping the ocean free of the bodies of dead animals due to its size.
These sharks were NEVER at the top of the food chain(s) BACK THEN and NOW. These sharks are NOT built and psychologically wired to challenge the killer whale types.
DO LET ME KNOW when you see these sharks shatter skulls of the killer whale types in trophic interactions: There are MORE examples I assure you. But these monsters DO NOT EXIST anymore. O. orca ecologically substituted macro-raptorial sperm whales [and genus Otodus] in modern ecosystems.
REFERENCES BLACK = FINE BLUE = CARELESS in citations RED = Dubious
Benites-Palomino, A., Velez-Juarbe, J., Altamirano-Sierra, A., Collareta, A., Carrillo-Briceño, J. D., & Urbina, M. (2022). Sperm whales (Physeteroidea) from the Pisco Formation, Peru, and their trophic role as fat sources for late Miocene sharks. Proceedings of the Royal Society B, 289(1977), 20220774. Bianucci, G., & Collareta, A. (2022). An overview of the fossil record of cetaceans from the East Pisco Basin (Peru). Bollettino della Società Paleontologica Italiana, 61(1), 20.
Collareta, A., Lambert, O., Marx, F. G., de Muizon, C., Varas-Malca, R., Landini, W., ... & Bianucci, G. (2021). Vertebrate Palaeoecology of the Pisco Formation (miocene, Peru): glimpses into the ancient humboldt Current ecosystem. Journal of Marine Science and Engineering, 9(11), 1188.
Del-Río, C. J., & Martínez, S. (2021). Diversity and biostratigraphy of the late Oligocene-late Miocene sand dollars (Echinoidea: Scutelliformes) of Argentina and Uruguay. Revista de Biología Tropical, 69, 35-50. Geisler, J. H., Colbert, M. W., & Carew, J. L. (2014). A new fossil species supports an early origin for toothed whale echolocation. Nature, 508(7496), 383-386.
Gutstein, C. S., Horwitz, F. E., Valenzuela-Toro, A. M., & Figueroa-Bravo, C. P. (2015). Cetáceos fósiles de Chile: context evolutivo y paleobiogeográfico. Publicación Ocasional del Museo Nacional de Historia Natural, Chile, 63, 339-387. Govender, R. (2021). Early Pliocene fossil cetaceans from hondeklip bay, namaqualand, South Africa. Historical Biology, 33(4), 574-593. Lambert, O., Bianucci, G., & De Muizon, C. (2017). Macroraptorial sperm whales (cetacea, odontoceti, physeteroidea) from the miocene of peru. Zoological Journal of the Linnean Society, 179(2), 404-474.
Pyenson, N. D., Cozzuol, M., Gutstein, C. S., Le roux J., J.F. Parham, J. F., Rubilar-rogers, D., SUÁREZ, M. E. (2011). New late Miocene marine tetrapods and the origin of the Bahía Inglesa Formation bonebed from the Atacama Desert of Chile. Ameghiniana 48(4): R48.
Pyenson, N. D. (2017). The ecological rise of whales chronicled by the fossil record. Current Biology, 27(11), R558-R564.
Piazza, D. S., Agnolin, F. L., & Lucero, S. (2018). First record of a macroraptorial sperm whale (Cetacea, Physeteroidea) from the Miocene of Argentina. Revista Brasileira de Paleontologia, 21(3), 276–280.
Serio, C., Castiglione, S., Tesone, G., Piccolo, M., Melchionna, M., Mondanaro, A., ... & Raia, P. (2019). Macroevolution of toothed whales exceptional relative brain size. Evolutionary Biology, 46(4), 332-342.
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Post by Grey on Oct 8, 2022 19:40:18 GMT 5
Looking at this abstract at the last SVP, it seems Livyatan-like forms did live in the northern hemisphere.  I tend to think those giant carnivorous phyeteroids may have been pelagic, preying on beaked whales, which could explain the relative rarity of their fossils. |
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Post by Life on Oct 9, 2022 3:31:39 GMT 5
Looking at this abstract at the last SVP, it seems Livyatan-like forms did live in the northern hemisphere. This tooth is very large but more information is needed to be certain. Teeth identified as aff. Livyatan sp. by Piazza et al (2018) have following dimensions:
Specimen MML 882
Maximum height as preserved (MH) = 142 mm
Maximum diameter (MW) = 74 mm
Specimen BAR-2601
Maximum height as preserved (MH) = 178 mm
Maximum diameter (MW): 72 mm
PROBLEM = These teeth can be attributed to Scaldicetus
The macro-raptorial physeteroid Scaldicetus caretti was found to be armed with teeth of varying sizes in its jaw structure: "As in other physeteroids, tooth dimensions vary markedly in this specimen: the total length of the root ranges from 106.9 to 203.5 mm, the maximum diameter of the root from 32.1 to 73.3 mm, the maximum diameter of the crown at its base from 16.0 to 32.5 mm, and the maximum total length reaches 233 mm (Table 1; Fig. 1)." - (Lambert & Bianucci, 2019)
Largest teeth of S. caretti such as W and X (~ 235 mm in MH and 72 mm in MW) give the impression of a Livyatan-like form when viewed in isolation. Teeth of S. caretti show damage and occlusal facets indicating consumption of large-bodied animals as a norm.
Scaldicetus is a genus encompassing several species (Hirota and Barnes, 1994) as noted below:
1. S. caretti
2. S. grandis
3. S. mortezelensis
4. S. bellunensis
5. S. bolxanensis 6. S. lodgei
7. S. macgeei
8. S. shigensis
Scaldicetus was well-established in the Northern hemisphere and managed to achieve cosmopolitan distribution according to Toscano et al (2013):
Figura 7. Distribución global de restos de Scaldicetus y áreas habitadas por Orcinus orca (modificado de Dahlheim y Hening, 1999; Lambert et al., 2008 y 2010; Paleobiology Database, 2012).
But some of the species attributed to Scaldicetus were renamed: S. mortezelensis -> Eudelphis mortezelensis (Peri et al., 2022) S. shigensis -> Brygmophyseter shigensis (Peri et al., 2022)
PROBLEM = UNCERTAIN TAXONOMIC ASSIGNMENTS and COMPLEXITY
- - - - - NOTE: O. orca eco-types do NOT seem to mate with each other and also have distinct dietary preferences.
Abstract of Moura et al (2014) for reference:
"The evolution of diversity in the marine ecosystem is poorly understood, given the relatively high potential for connectivity, especially for highly mobile species such as whales and dolphins. The killer whale (Orcinus orca) has a worldwide distribution, and individual social groups travel over a wide geographic range. Even so, regional populations have been shown to be genetically differentiated, including among different foraging specialists (ecotypes) in sympatry. Given the strong matrifocal social structure of this species together with strong resource specializations, understanding the process of differentiation will require an understanding of the relative importance of both genetic drift and local adaptation. Here we provide a high-resolution analysis based on nuclear single-nucleotide polymorphic markers and inference about differentiation at both neutral loci and those potentially under selection. We find that all population comparisons, within or among foraging ecotypes, show significant differentiation, including populations in parapatry and sympatry. Loci putatively under selection show a different pattern of structure compared to neutral loci and are associated with gene ontology terms reflecting physiologically relevant functions (e.g. related to digestion). The pattern of differentiation for one ecotype in the North Pacific suggests local adaptation and shows some fixed differences among sympatric ecotypes. We suggest that differential habitat use and resource specializations have promoted sufficient isolation to allow differential evolution at neutral and functional loci, but that the process is recent and dependent on both selection and drift."
I tend to think those giant carnivorous phyeteroids may have been pelagic, preying on beaked whales, which could explain the relative rarity of their fossils. Astute observation.
Livyatan-like forms might be pelagic and consuming beaked whales (Ziphiidae). This strategy and trophic position could help avoid competition (and reduce interactions) with genus Otodus.
Interestingly, beaked whale species Messapicetus gregarius is found to co-exist with Livyatan melvillei in the P1 allomember of the Pisco Formation of Peru (Bianucci & Collareta, 2022), but BOTH are NOT found in the P0 allomember of the Pisco Formation of Peru (Bianucci & Collareta, 2022).  Lambert et al (2018) made a case for parallel progressive emergence of characters related to a specialization toward deep diving and suction feeding in physeteroids and ziphiids as well as macroraptorial sperm whales preying on ziphiids in the Miocene epoch:
Figure 2. Artistic reconstructions of the macroraptorial sperm whale Livyatan melvillei (A) and the raptorial snapping beaked whale Messapicetus gregarius (B), both from the late Miocene of Peru, taken from Lambert et al. (2017) and Lambert et al. (2015). © A. Gennari.
- - - - - - Macro-raptorial physeteroids might have achieved speciation and reduced competition with each other as well as with OTHER macro-raptorial life-forms including genus Otodus. This is reasonable explanation of morphological variations in prehistoric physeteroids.
When a large number of macro-raptorial animals CO-EXIST at a particular point in time, MOST try to REDUCE COMPETITION through speciation. This is EXACTLY what the O. orca eco-types seem to be doing in the present (see above).
Many simply look at the jaw structure and teeth of an extinct cetacean and will LEAP to conclusion: "Hey, this thing was providing competition to genus Otodus and more."
BASED ON? Why every macro-raptorial life-form would want to compete with genus Otodus? Similarly, why every macro-raptorial life-form would want to risk clashes with genus Otodus?
REFERENCES Behl, R. J. (2012, April). The Monterey Formation of California: new research directions. In AAPG Annual Convention and Exhibition, Long Beach, California. Bianucci, G., & Collareta, A. (2022). An overview of the fossil record of cetaceans from the East Pisco Basin (Peru). Bollettino della Società Paleontologica Italiana, 61(1), 20. Hirota, K., & Barnes, L. G. (1994). A new species of Middle Miocene sperm whale of the genus Scaldicetus (Cetacea; Physeteridae) from Shiga‐mura, Japan. Island Arc, 3(4), 453-472.
Lambert, O., Bianucci, G., & de Muizon, C. (2018). Sperm and beaked whales, Evolution. In Encyclopedia of Marine Mammals (pp. 916-918). Academic Press.
Lambert, O., & Bianucci, G. (2019). How to break a sperm whale’s teeth: dental damage in a large Miocene physeteroid from the North Sea Basin. Journal of Vertebrate Paleontology, 39(4), e1660987. Moura, A. E., Kenny, J. G., Chaudhuri, R., Hughes, M. A., J. Welch, A., Reisinger, R. R., ... & Hoelzel, A. R. (2014). Population genomics of the killer whale indicates ecotype evolution in sympatry involving both selection and drift. Molecular Ecology, 23(21), 5179-5192.
Piazza, D. S., Agnolin, F. L., & Lucero, S. (2018). First record of a macroraptorial sperm whale (Cetacea, Physeteroidea) from the Miocene of Argentina. Revista Brasileira de Paleontologia, 21(3), 276–280. Peri, E., Collareta, A., Aringhieri, G., Caramella, D., Foresi, L. M., & Bianucci, G. (2022). A new physeteroid cetacean from the Lower Miocene of southern Italy: CT imaging, retrodeformation, systematics and palaeobiology of a sperm whale from the Pietra leccese. Bollettino della Società Paleontologica Italiana, 61(2), 188.
Toscano, A., Abad, M., Ruiz, F., Muñiz, F., Álvarez, G., García, E. X. M., & Caro, J. A. (2013). New remains of upper Miocene Scaldicetus (Cetacea, Odontoceti, Physeteridae), western sector of the Guadalquivir basin (southern Spain). Revista mexicana de ciencias geológicas, 30(2), 436-445.
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Post by Grey on Oct 9, 2022 10:57:05 GMT 5
I suspect the researchers involved have enough diagnostic to distinct Livyatan and Scaldicetus teeth.
It should be noted that those isolated teeth could belong to Livyatan-like forms despite not being as large as the largest teeth in the type specimen :
- it has smaller teeth in its mandible than 36 cm long, 11 cm diamater.
- even if the isolated teeth do correspond in position and shape to the largest teeth in the type's mandible, maybe the holotype was quite large in itself, its upper teeth are not preserved except for the upper roots in the alveoli, the preserved upper teeth in the holotype may well have been larger than the 36 cm teeth from the mandible.
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Post by Infinity Blade on Oct 26, 2022 5:03:12 GMT 5
I normally avoid making new posts in the animal vs animal section of this forum, but I couldn't help but post this ( source->). Here, Livyatan is based on the proportions of Brygmophyseter, resulting in an animal about 12.5 meters long in total length. The same guy who created this has a size comparison of various megalodon specimens of different age ( link->), and a 12.4 meter old juvenile megalodon is the closest to the sperm whale in length.  Please don't go rabid over this. |
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Post by Grey on Oct 28, 2022 2:23:06 GMT 5
Hopefully this kind of work will motivate further reviewed reconstructions of those raptorial sperm whales. Boessenecker seems to agree. I've read that Livyatan is perhaps closer to kogiids, using their proportions might be interesting.
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Post by elosha11 on Oct 28, 2022 16:04:31 GMT 5
^Yep.  |
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