tag:blogger.com,1999:blog-1953405279736337089.post4799607808122715189..comments2024-03-29T03:21:04.512-06:00Comments on The Coastal Paleontologist: Shark-bitten dolphin skullRobert Boesseneckerhttp://www.blogger.com/profile/04157434108254005433noreply@blogger.comBlogger16125tag:blogger.com,1999:blog-1953405279736337089.post-42620314415671220742011-03-09T08:25:00.350-07:002011-03-09T08:25:00.350-07:00Those are really cool!
Good luck finding more!Those are really cool!<br />Good luck finding more!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-33139901982993529812011-02-14T17:26:45.031-07:002011-02-14T17:26:45.031-07:00Those are all important characteristics of Monodon...Those are all important characteristics of Monodontids. As for Monodon - Monodon practically lacks a fossil record, and every other known monodontid (modern or fossil) exhibits well defined maxillary exposure anterior to the nares. I've already compared it with monodontids - there aren't many; none of them look like this, and they're all much larger.<br /><br />Otherwise, it does share some features in common with phocoenids, and in fact, I had originally identified it as a phocoenid; it has features of both Phocoenidae and Delphinidae.Robert Boesseneckerhttps://www.blogger.com/profile/04157434108254005433noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-73650712620756500932011-02-14T08:39:43.237-07:002011-02-14T08:39:43.237-07:00The first of these traits is the most important. H...The first of these traits is the most important. However, in extant narwhals proximal parts of premaxillae can be totally fused with maxillae, so the sutures anterior to nares can be not visible. <br /><br />I do not insist it is a monodontid but it can be interesting to compare them (if you have access to Denebola skulls), as well as with basal phocoenids.<br /><br />Thank you.Pavelhttps://www.blogger.com/profile/14108416061639767499noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-47743999670195812132011-02-14T01:43:39.006-07:002011-02-14T01:43:39.006-07:00Pavel,
It lacks several features of monodontids, ...Pavel,<br /><br />It lacks several features of monodontids, including maxillae exposed along the anterior margin of the bony nares, deeply entrenched sulci on the premaxillae, a wide rostrum, an elongate temporal fossa, and among other features, it's very small (i.e. 6-7" wide at the orbits) and has a rostrum that is way too long and narrow.Robert Boesseneckerhttps://www.blogger.com/profile/04157434108254005433noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-86564120076909561842011-02-13T09:19:47.516-07:002011-02-13T09:19:47.516-07:00Dear Robert,
Thank you very much for your posts a...Dear Robert,<br /><br />Thank you very much for your posts and photos. <br /><br />Could this small dolphin be a monodontid? Or saying in other words, why it could not be a monodontid?<br /><br />PavelPavelhttps://www.blogger.com/profile/14108416061639767499noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-87612718603527799072010-11-17T14:39:02.180-07:002010-11-17T14:39:02.180-07:00Thanks Robert, that's very helpful.
I'm dr...Thanks Robert, that's very helpful.<br />I'm drawing from Frederick Grassle's theories on predictable ecosystems leading to greater diversity, where very generally, long-term stability of marine ecosystems vs. terrestrial ecosystems lead to greater species diversity. Ref: J. Frederick Grassle and Howard L. Sanders 1973<br />Woods Hole Oceanographic Institute<br />Life histories and the role of disturbance.<br />While looking up Bianucci, I also just found Whales, whaling, and ocean ecosystems, ed. by James Estes, which should be very informative.<br />Thanks again, and I look forward to more visits to your informative blog.<br />HowardHoward Garretthttps://www.blogger.com/profile/15694095662928156804noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-58529205331233182762010-11-16T21:11:18.512-07:002010-11-16T21:11:18.512-07:00Nevermind, I misread your comment about specialize...Nevermind, I misread your comment about specialized niches. Whoops!Robert Boesseneckerhttps://www.blogger.com/profile/04157434108254005433noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-13960841369726668702010-11-16T21:10:10.227-07:002010-11-16T21:10:10.227-07:00Hi Howard,
There aren't any bona fide records...Hi Howard,<br /><br />There aren't any bona fide records of Orcinus older than 2-3 Ma; there is a possible early Pliocene tooth reported from Japan (~3-5 Ma), but who knows, odontocete teeth aren't terribly diagnostic anyway. The only bona fide pre-Pleistocene record is Orcinus citoniensis, from the late Pliocene of Italy. There is a single earbone of this animal from the Early Pleistocene Red Crag of England. The reference is included below.<br /><br />As far as radiating into ever more specialized niches - I disagree. The cetacean fossil record shows a number of different successive cetacean faunas through time, and through a very UNstable marine environment (End-Eocene climate crash, opening/closure of the Panama seaway, and Pleistocene changes in sea level (and the Messinian Salinity Crisis in the Mediterranean). Furthermore, there are many extinct bizarre, highly specialized cetaceans and other marine mammals that lived during the Pliocene, which have subsequently gone extinct, presumably in favor of more generalized extant cetaceans.<br /><br />Bianucci. 1996. The Odontoceti (Mammalia, Cetacea) from Italian Pliocene systematics and phylogenesis of Delphinidae. Palaeontologrphia Italia 83:73-167Robert Boesseneckerhttps://www.blogger.com/profile/04157434108254005433noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-61670038147682032902010-11-16T21:00:05.968-07:002010-11-16T21:00:05.968-07:00Robert, I found your blog via a search for llanoce...Robert, I found your blog via a search for llanocetus. I'm working on a slide show here on Whidbey Island, on "Resident and Transient orcas - How did that happen?" <br />For context I'm giving the evolutionary history of cetacea, with emphasis on the way species radiated into ever more obscure niches in the relatively stable marine environment and made amazing adaptations to specialize on a narrow range of prey.<br />I haven't been able to find any reference to when Orcinus orca originated. I'm assuming the essentially modern orcas arrived around 6-10 mya, but other than the advent of modern dolphins 12-15 mya (is that right?), and one hearsay report of an orca tooth from 6 mya, I can't find anything definitive on when modern orcas arrived. Do you have any clues or theories on that?<br />Thanks.<br />Howard<br />Orca NetworkHoward Garretthttps://www.blogger.com/profile/15694095662928156804noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-32128893158857737832010-11-16T13:03:44.994-07:002010-11-16T13:03:44.994-07:00Hey Chuck,
That tooth is from the very base of th...Hey Chuck,<br /><br />That tooth is from the very base of the Purisima Formation - I'll send you a picture later today or tonight; It's huge.<br /><br />Regarding mollusk-vertebrate associations, I know of two from the same locality. One is the whale-fall assemblage that Frank discovered in the 1990's, and I found a large concretion a couple years ago (which I got a few chunks of) that was packed with Naticid snails and fish bone fragments, and since it was only ~60 feet away from Frank's whale fall assemblage, I'd suspect they belong to the same assemblage.Robert Boesseneckerhttps://www.blogger.com/profile/04157434108254005433noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-36223526460275575922010-11-15T12:58:25.185-07:002010-11-15T12:58:25.185-07:00So Bobby,
Please post a picture of the shark too...So Bobby, <br /><br />Please post a picture of the shark tooth you mention early on in this post and I was wondering if you ever see mollusks associated with any of the skeletal elements from the Purisima. Frank mentioned he had and I'd like to document them if we can find a site with them again. Thanks. BTW - good work.Unknownhttps://www.blogger.com/profile/17032269826601277084noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-35339970292327918752010-11-14T19:45:31.881-07:002010-11-14T19:45:31.881-07:00Yeah, monodontids do appear to be pretty rare - la...Yeah, monodontids do appear to be pretty rare - last year I tallied up odontocete periotics (in private and museum collections) from the Purisima Formation, and monodontids (all Denebola) comprise 8% of the assemblage (N=120). I'm genuinely surprised that monodontids haven't been reported from the Pliocene of Florida; I guess that's what part of Whitmore's (1994) hypothesis about the range of Pliocene Delphinapterus was based on (showing up in North Carolina, but not in Florida). There is also some Pleistocene material from Canada, including a nearly complete skeleton called "Felix". From what I remember, there is also some material from Baja California listed by Barnes (1998).Robert Boesseneckerhttps://www.blogger.com/profile/04157434108254005433noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-10610617661728969432010-11-13T06:45:22.107-07:002010-11-13T06:45:22.107-07:00Yes, Monodon and a monodontid from the Early Plioc...Yes, <i>Monodon</i> and a monodontid from the Early Pliocene of Belgium have the eminences (Lambert & Gigase, 2007); looking at Barnes (1984) <i>Denebola</i> doesn't seem to have it, just like <i>Delphinapterus</i>. <br />Its good to know that there are more skulls referable to <i>Denebola</i>, otherwise monodontids seem to have a pretty scanty fossil record. The thing from the San Mateo Fm is the one reported in Barnes & Deméré (1991), they do mention that it is closest to <i>Denebola</i>. As for over here in the east coast, there's some material from the Yorktown Fm reported in Withmore & Kantenbach (2008).J. Velez-Juarbehttps://www.blogger.com/profile/13939389115952799046noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-13915639086770397192010-11-12T12:57:54.476-07:002010-11-12T12:57:54.476-07:00Morgan - thanks dude! Yes, I'm pretty proud of...Morgan - thanks dude! Yes, I'm pretty proud of it. It's definitely one of the prettier skulls I've collected.<br /><br />Jorge - Albireo has huge premaxillary eminences, and I've heard of some monodontids as having them (Monodon, maybe; Delphinapterus doesn't seem to, and I can't recall about Denebola). If delphinids and phocoenids are that closely related, than perhaps it might not be too surprising to have mild premaxillary eminences in a basal delphinid (or, on the other hand, this relatively high degree of cranial asymmetry in a basal phocoenid).<br /><br />Denebola is known from the Purisima Formation as well; there are a couple skulls, and I know of at least a dozen periotics from the Purisima. I'm not sure if its brachycephala or not, because the skull still needs to be prepared (a probable project for me next year). There is some kind of delphinapterine that Larry Barnes has from the San Mateo Formation, and I'd put good money down that its Denebola (although I must confess I haven't seen it, and probably won't be able to for some time). There's also some periotics and a pair of partial dentaries from the San Diego Formation of some kind of delphinapterine- although after seeing my poster at SVP 2009, Tom Demere thought it might be some kind of globicephaline (although the dentery to me appeared to be too straight, then again - I have one horrible photo of it in its specimen tray, and not in occlusal aspect). Just describing San Diego monodontids would make a nice short paper on its own.Robert Boesseneckerhttps://www.blogger.com/profile/04157434108254005433noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-26257821708829953432010-11-12T12:43:30.716-07:002010-11-12T12:43:30.716-07:00Hi Robert,
That is a nice looking skull! Doesn...Hi Robert,<br /><br />That is a nice looking skull! Doesn't <i>Albireo</i> have those bosses too? <br />I've been wanting to ask you, have you found any monodontid (skulls)? As far as I know there is only <i>Denebola brachycephala</i> from the Late Miocene of Isla Cedros and an undescribed <i>Denebola</i>-like thing from CA. Most other pre-Pleistocene monodontids seem to be based on periotics or very incomplete material.J. Velez-Juarbehttps://www.blogger.com/profile/13939389115952799046noreply@blogger.comtag:blogger.com,1999:blog-1953405279736337089.post-3852366545743763582010-11-12T07:21:24.109-07:002010-11-12T07:21:24.109-07:00wow...that is a beautiful skullwow...that is a beautiful skullUnknownhttps://www.blogger.com/profile/10767952407881212708noreply@blogger.com