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James D. Watson does it again or The sad twilight of a world-class scientist

The Bald Scientist -

**Sigh** This is getting really old. It is also sad. Every one of us wants to be remembered. It is just human nature. In the particular case of us scientists, we generally want to be remembered by our contributions, however minor, to the better understanding of nature. In the case of ground-breaking, paradigm-shifting discoveries thereContinue reading "James D. Watson does it again or The sad twilight of a world-class scientist"

To all my fellow Spanish-speaking biology enthusiasts!

The Bald Scientist -

This is a message to all my fellow Spanish-speaking biology enthusiasts! I will be interviewed by the talented science communicator Ms. Sofía Martínez Villalpando in her YouTube channel “The Biologist Apprentice” this Friday January 11 at 7pm EST. It should be fun! (:-) ~~~~~ **If you like what I write, kindly spread the word aboutContinue reading "To all my fellow Spanish-speaking biology enthusiasts!"

Merry Everything!

The Bald Scientist -

Hello All! In these time of the year, in an admittedly arbitrary way, most of us reflect on our lives and what the previous year has brought. These are uncertain, sad, perhaps even dangerous times. We all have people whom we have lost and are dearly missed. We all have went through challenges, triumphs, andContinue reading "Merry Everything!"

#VOTE

The Bald Scientist -

When you are at risk of being shot at school, work, the supermarket, church, and even at f’ing yoga class, among many other places, something is clearly wrong. Any person with a bare inkling of honesty and human decency will admit to that. #VOTE Advertisements

New publications on middle Miocene walruses of southern California and Baja California Sur

Caribbean Paleobiology -

One of the first things I did when I started working at the Natural History Museum of Los Angeles County (MNHLA) was getting familiarized with the collection of fossil marine mammals. Coming in I knew it was (and is) one of the best in the World, but I was still surprised with the extent and amount of fossil pinnipeds. Pinnipeds is the name given to the group that include walruses (Odobenidae), sea lions/fur seals (Otariidae), seals (Phocidae) and a few other related, but extinct groups (e.g. desmatophocids). My first thought was that I would eventually get around to work on pinnipeds after several years, thinking I would first focus more on the cetaceans and herbivorous marine mammals. But then the more I looked at pinnipeds, the more interested I became in their fossil record and what new information we could learn about their evolutionary history based on the specimens at NHMLA and other nearby collections. And so, my interest in this group grew and I found myself working on pinnipeds much sooner than I had originally planned. My first scientific publication on the subject was last year when I described the pan-otariid Eotaria citrica, based on a well-preserved mandible and lower dentition which was published in the open access journal PeerJ (you can download the paper here (Velez-Juarbe, 2017) and also read my post about it).
On the left, the type mandible of Eotaria citrica; on the right, a life reconstruction of how it might have looked like.
The dwarf walrus from Baja California SurMore recently, my colleague Fernando Salinas-Márquez and I described a new species of walrus that we dubbed Nanodobenus arandai, aka Smallrus or Aranda's dwarf walrus if, you know, you're not into the whole brevity thing.Myself, holding the type (name-bearing specimen) of Nanodobenus arandai; on the right, the skull of the living walrus, Odobenus rosmarus.Nanodobenus comes from a very interesting locality in the Vizcaíno Península in Baja California Sur. It was collected from sediments that are part of the Tortugas Formation as exposed along Arroyo La Chiva (also known as Arroyo Tiburón) (Throughton, 1974; Applegate et al., 1979; Moreno-Ruiz and Carreño, 1994). The age range of this formation is somewhat uncertain, or more precisely, broader than I would prefer it to be, as it has been described as ranging from the middle to the late Miocene (Barnes, 1998). For this work, Fernando and I reviewed the scientific literature and were able to restrict its range to 15.7-9.2 Ma, which is admittedly still fairly broad, but we'll hopefully be able to get more precise dates in the not so distant future.  A more detailed view of the holotype mandible of Nanodobenus arandai, in lateral (top), medial (middle) and occlusal (bottom), views. Modified from Velez-Juarbe and Salinas-Márquez (2018:fig. 2). One of the most striking features of Nanodobenus was its small body length, which, based on measurements of the toothrow, was estimated to be around 1.65 m. This places it as the smallest odobenid known so far (see body size outlines below), with a body length more similar to that of the early otariid Pithanotaria starri and around the range of the living fur seal Callorhinus ursinus (Velez-Juarbe, 2017). The small body length of Nanodobenus seems to break a pattern in odobenid evolution, where body size increase seemed to be the norm throughout the mid-late Miocene, culminating in the gigantic walrus Pontolis magnus (Velez-Juarbe, 2017; Boessenecker and Churchill, 2018). The absence of Nanodobenus from contemporaneous units farther north in California could have been due to a number of reasons, like habitat preference, local endemism, or simply that they were there, but we still haven't identified its remains in these other units. Interestingly, dwarfism in odobenids seems to parallel a pattern observed in the South Pacific and the North Sea and Paratethys, where dwarf seals were sympatric with larger species.
Relationships and body sizes of odobenids. Modified from Velez-Juarbe and Salinas-Márquez (2018:fig. 4).Our paper describing Nanodobenus was published in the open access journal Royal Society Open Science, which means you can download it for free (Velez-Juarbe and Salinas-Márquez, 2018).
Pinnipeds of Sharktooth HillJust out today (10/19/2018) is my most recent publication. In it I describe in detail the lower jaw and dentition of the early odobenid Neotherium mirum - originally named by none other than Remington Kellogg in 1931 - in it, I also describe some other significant pinniped mandibles from the Sharktooth Hill Bonebed (STH). I've written about Sharktooth Hill before and I have to say it is one of the most amazing middle Miocene marine deposits in the World! This bonebed was deposited between 15.9-15.2 million years ago near Bakersfield, CA, and is one of the densest accumulations of marine vertebrates that we know of, with a fairly large number of taxa described so far (e.g. Kellogg, 1931; Howard, 1966; Mitchell, 1966; Barnes, 1988; Lynch and Parham, 2003; Pyenson et al., 2009; Velez-Juarbe, 2018).Pinniped remains abound in the Sharktooth Hill bonebed, with the second most common one being Neotherium mirum; however, relatively little is known of this species. The original description by Kellogg (1931) was based on postcranial elements, and since then a few papers have discussed and/or described some of its cranial and mandibular features (Mitchell and Tedford, 1973; Repenning and Tedford, 1977; Barnes, 1988; Deméré, 1994; Kohno et al., 1995). In my new publication I described the morphology of the mandible and lower teeth in detail, based on several specimens from the collections at the Natural History Museum of Los Angeles County and the University of California Museum of Paleontology (UCMP). One other aspect I set out to explore was wether Neotherium showed body size sexual dimorphism as previous authors had suggested (Repenning and Tedford, 1977; Barnes, 1988). The morphology of the lower jaw of Neotherium shows an interesting mix of characters, some which are shared with early pinnipedimorphs and others which it shares with more derived odobenids. Size difference amongst the several mandibles I studied support the hypothesis that the species is sexually dimorphic, with male mandibles being around 25% larger than the female mandibles. This was similar to the differences amongst male/female mandibles of Steller's sea lion (Eumetopias jubatus), but less extreme than those shown between males/females of California sea lion (Zalophus californianus).Various mandible of Neotherium mirum, representing male (A-D, F, and H), and female (E, G, and I) individuals. Modified from Velez-Juarbe (2018:fig. 1).Neotherium mirum is not the only pinniped known from the Sharktooth Hill Bonebed; two other walruses and two desmatophocids are also known from this unit. One of the other walruses is Pelagiarctos thomasi, which was a relatively large odobenid with fused mandibles and bulbous teeth; its morphology is still poorly known as only a few specimens are known, making it one of the rarest pinnipeds from this unit (Barnes, 1988; Boessenecker and Churchill, 2013). The second walrus is even rarer and was one of the other subjects of my paper. While browsing the collections I came across a mandible that did not look like any of the other STH pinnipeds, so I decided it would be an interesting addition and worthy of describing even if I couldn't pinpoint its precise id because of its incompleteness. This other mandible which I identified as belonging to some unknown odobenid was intermediate in size between male Neotherium mirum and Pelagiarctos thomasi, and showed some interesting characters regarding reduction of the postcanine dentition. Specifically, this unknown odobenid showed a bilobed first molar (m1) while still having double-rooted second through fourth premolars (p2-4). This pattern of root reduction departs form the usual pattern observed amongst odobenids where root simplification usually begins with the more anterior premolars and moves backwards towards the molars.Phylogenetic analysis showing relationships amongst odobenids and other pinnipeds, highlighting reduction of the postcanine teeth across the different groups. Modified from Velez-Juarbe (2018:fig. 5).Reduction and simplification of the postcanine dentition is a phenomenon observed across different pinniped groups (Repenning and Tedford, 1977; Barnes, 1989; Deméré, 1994; Barnes et al., 2006; Boessenecker, 2011). Based on the analysis in my paper it seems that simplification/reduction of the postcanine roots in odobenids has occurred several times throughout their evolutionary history (see phylogenetic tree above).The other pinnipeds from STH are the desmatophocids Allodesmus kernensis and A. cf. A. sadoensis (or A. cf. A. sinanoensis according to Tonomori et al., 2018). The precise number of valid species of Allodesmus from STH has been a issue discussed in the literature for quite some time, with up to three species considered valid: Allodesmus kernensis, A. kelloggi, and A. gracilis (Kellogg, 1922; Mitchell, 1966; Barnes and Hirota, 1995). Fortunately this was resolved recently by Boessenecker and Churchill (2018) who determined that A. kelloggi and A. gracilis are junior synonyms of A. kernensis. In their study they also determined that the morphology of a fragmentary mandible that had been referred by Barnes (1972) as 'Desmatophocine B' was more consistent with Allodesmus sadoensis and referred to it as A. cf. A. sadoensis. The presence of this species in California, otherwise known from middle Miocene deposits in Japan, was further confirmed in my study, where I described and assigned a second mandible to that particular taxon. However, the mandible I assigned to this species was quite rare, with only four postcanine teeth, instead of the more normal five or six; did this represents a more extreme case of tooth reduction or a pathology? We can't tell for now, but hopefully additional specimens will turn up in other collections which will help clarify this. So at present there are up to five species of pinnipeds that were likely sympatric during the deposition of the Sharktooth Hill Bonebed, making it a fairly diverse pinniped assemblage, and unlike anything we see today, especially since there's only one living species of walrus.Mandibles representing pinnipeds from the Sharktooth Hill Bonebed. Modified from Velez-Juarbe (2018:fig. 6).This paper on Neotherium and other STH pinnipeds is out on Journal of Vertebrate Paleontology, if you are interested in a PDF feel free to email me and I'll send it your way!
The Titan walrus of Orange CountyOut this month too was the publication another work with colleagues Isaac Magallanes, Jim Parham and Gabe Santos. In this work (Magallanes et al., 2018) we described a fossil odobenid which we dubbed Titanotaria orangensis from the late Miocene of Orange County, California. In addition to describing this interesting new species, we took a closer look at the fossil record of odobenids as well as revised the taxonomy of the group. I was honored to have been invited to participate in this project and I will be discussing it in more detail in a future post. Meanwhile, you can download the PDF and start reading it as it is open access. 
Even more marine mammal news coming soon, so stay tuned!!!!
References
Applegate, S. P., I. Ferrusquía-Villafranca, and L. Espinoza-Arrubaena. 1979. Preliminary observations on the geology and paleontology of the Arroyo Tiburón area, Bahía de Asunción, Baja California Sur, Mexico; pp. 113-115 in P. L. Abbott, and R. G. Gastil (eds.), Baja California Geology. Field Guides and Papers, Geological Society of America Annual Meeting. San Diego State University Publication, San Diego, CA.
Barnes, L. G. 1972. Miocene Desmatophocinae (Mammalia: Carnivora) from California. University of California Publications in Geological Sciences 89:1-76.
Barnes, L. G. 1988. A new fossil pinniped (Mammalia: Otariidae) from the middle Miocene Sharktooth Hill Bonebed, California. Natural History Museum of Los Angeles County Contributions in Science 396:1-11.
Barnes, L. G. 1989. A new enaliarctine pinniped from the Astoria Formation, Oregon, and a classification of the Otariidae (Mammalia: Carnivora). Natural History Museum of Los Angeles County Contributions in Science 403:1-26.
Barnes, L. G. 1998. The sequence of fossil marine mammal assemblages in Mexico; pp. 26-79 in O. Carranza-Castañeda and D. A. Córdoba-Méndez (eds.), Avances en Investigación, Paleontología de Vertebrados. Publicación Especial 1, Instituto de Investigaciones en Ciencias de la Tierra, Universidad Autónoma del Estado de Hidalgo, Mexico.
Barnes, L. G., and K. Hirota. 1995. Miocene pinnipeds of the otariid subfamily Allodesminae in the North Pacific Ocean: systematics and relationships. Island Arc 3:329-360.
Barnes, L. G., C. E. Ray, and I. A. Koretsky. 2006. A new Pliocene sea lion, Proterozetes ulysses from Oregon, U.S.A.; pp. 57-77 in Z. Csiki (ed.), Mesozoic and Cenozoic Vertebrates and Paleoenvironments: Tributes to the Career of Prof. Dan Grigorescu. Bucharest, Romania.
Boessenecker, R. W. 2011. New records of the fur seal Callorhinus (Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of Northern California and comments on otariid dental evolution. Journal of Vertebrate Paleontology 31:454-467.
Boessenecker, R. W., and M. Churchill. 2013. A reevaluation of the morphology, paleoecology, and phylogenetic relationships of the enigmatic walrus Pelagiarctos. PLoS ONE 8:e54311.
Boessenecker, R. W., and M. Churchill. 2018. The last of the desmatophocid seals: a new species of Allodesmus from the upper Miocene of Washington, USA, and a revision of the taxonomy of Desmatophocidae. Zoological Journal of the Linnean Society 184:211-235.
Deméré, T. 1994. The family Odobenidae: a phylogenetic analysis of fossil and living taxa. Proceedings of the San Diego Society of Natural History 29:99-123.
Howard, H. 1966. Additional avian records from the Miocene of Sharktooth Hill, California. Natural History Museum of Los Angeles County Contributions in Science 114:1-11.
Kellogg, R. 1922. Pinnipeds from Miocene and Pleistocene deposits of California. University of California Publications in Geological Sciences 13:23-132.
Kellogg, R. 1931. Pelagic mammals from the Temblor Formation of the Kern River region, California. Proceedings of the California Academy of Sciences 19:217-397.
Lynch, S. C., and J. F. Parham. 2003. The first report of hard-shelled sea turtles (Cheloniidae sensu lato) from the Miocene of California, including a new species (Euclastes hutchisoni) with unusually plesiomorphic characters. PaleoBios 23:21-35.
Magallanes, I., J. F. Parham, G.-P. Santos, and J. Velez-Juarbe. 2018. A new tuskless walrus from the Miocene of Orange County, California, with comments on the diversity and taxonomy of odobenids. PeerJ 6:e5708.
Mitchell, E. D. 1966. The Miocene pinniped Allodesmus. University of California Publications in Geological Sciences 61:1-46.
Moreno-Ruiz, J. L., and A. L. Carreño. 1994. Diatom biostratigraphy of Bahía Asunción, Baja California Sur, Mexico. Revista Mexicana de Ciencias Geológicas 11:243-252.
Pyenson, N. D., R. B. Irmis, L. G. Barnes, E. D. Mitchell, S. A. McLeod, and J. H. Lipps. 2009. Origin of a widespread marine bonebed deposited during the middle Miocene Climatic Optimum. Geology 37:519-522.
Repenning, C. A., and R. H. Tedford. 1977. Otarioid seals of the Neogene. United States Geological Survey Professional Paper 992:1-87.
Tonomori, W., H. Sawamura, T. Sato, and N. Kohno. 2018. A new Miocene pinniped Allodesmus (Mammalia: Carnivora) from Hokkaido, northern Japan. Royal Society Open Science 5:172440.
Throughton, G. H. 1974. Stratigraphy of the Vizcaíno Peninsula near Asunción Bay, Territorio de Baja California Sur, Mexico. MSc thesis, San Diego State University, 83 pp.
Velez-Juarbe, J. 2017. Eotaria citrica, sp. nov., a new stem otariid from the 'Topanga' Formation of southern California. PeerJ 5:e3022. doi:10.7717/peerj.3022
Velez-Juarbe, J. 2018. New data on the early odobenid Neotherium mirum Kellogg, 1931, and other pinniped remains from the Sharktooth Hill Bonebed, California. Journal of Vertebrate Paleontology doi:10.1080/02724634.2018.1481080
Velez-Juarbe, J., and F. M. Salinas-Márquez. 2018. A dwarf walrus from the Miocene of Baja California Sur, Mexico. Royal Society Open Science 5:180423. 

Strange Survivors Kindle and audio CD versions on sale

The Bald Scientist -

This is not my doing (I have no idea how amazon sets prices), but the Kindle and audio CD versions of Strange Survivors are on sale right now at $9.99 and $9.00 respectively… I have no idea when will these prices be changed. This is a public service announcement courtesy of Baldscientist (:-). To accessContinue reading "Strange Survivors Kindle and audio CD versions on sale"

These Images Reveal What the Human Eye Can’t See | Time

Lueny Morell -

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