The photo of the Northern ground hornbill Bucorvus abyssinicus featured here yesterday was posted entirely on a whim. And I figured that I didn't need to say much about the species, nor about ground hornbills in general, given that they've been discussed at length on Tet Zoo before. But then I realised that the only in-depth treatment of ground hornbills at Tet Zoo comes from ver 1, and thus dates to 2006. That's three years ago. Given that so much has changed in terms of Tet Zoo's readership, it's clearly time to re-post this old, classic article. If you remember it from the first time round: sorry, but do note that I've added a bit of new stuff here and there. I've also removed all the stuff about dinosauroids, as I don't want to go over that again (see the link at the bottom for the full story).
On more than one occasion now, I've found myself staring through cage bars at a menacing, striding bipedal predator, strikingly coloured in black and brick red. This predator does all kinds of neat things if you watch it for long enough. On one occasion, it picked up a dead mouse and threw it around, apparently for no reason other than for its own enjoyment. It then picked up a stone in its mouth and repeatedly dropped it onto the little furry corpse. On another occasion, I managed to get one to engage in what looked like play behaviour: it not only ran in parallel to me, it lay down on one side, raised an arm, and then passed leaves and twigs through the fence in my direction. If the speculations of some ornithologists are to be believed, then the awesome feathered dinosaurs I've watched so often at the zoo - Southern ground hornbills Bucorvus leadbeateri - are avian 'pseudo-hominids'.
Ground hornbills are big birds, reaching 4 kg in weight and with a wingspan that can reach 2 m. They're entirely black except for their white primaries and the bright red fleshy wattles that decorate their faces and throats (the second species in the genus Bucorvus [which means 'ox crow'], the Northern or Abyssinian ground hornbill, has red and blue facial skin in males and all-blue skin in females). Inhabiting the wooded savannahs of tropical southern African, Southern ground hornbills forage on the ground, picking up animal prey from among the grass or from low-growing vegetation. They grab everything from insects, snails, arachnids and worms to lizards, snakes, tortoises and even squirrels and hares. They may also excavate wasp and bee nests. Prey is grasped delicately with the forceps-like bill tips. Snakes and other dangerous prey may be repeatedly squeezed at the jaw tips until dead. Prey is swallowed using a 'throw and gulp' action [adjacent photo courtesy of Mark Witton].
Precision gripping, reinforced jaw joints, and sunshade eyelashes
The jaws are laterally compressed and gently curved, and though the bill tips meet when the jaws are in occlusion, a gap is usually visible part way along the jaws, even when they're closed. The size of the gap seems variable between individuals, and it's much less pronounced than that seen in some other hornbills, like the red-billed and yellow-billed Tockus species. All hornbills share a heavily reinforced bill: the palatal surface forms a complete bony roof to the mouth, and all of the palatal bones are fused together. This is a modified version of the desmognathous condition and it presumably evolved to provide mechanical support for the bill: among so-called 'higher landbirds' it's present in birds that kill and consume active prey, as well as in forms that beat prey dead against a perch. Among this lot are motmots, bee-eaters and rollers. This isn't the whole story behind the desmognathous palate incidentally, as it's also present in waterfowl, ibises, spoonbills, pelicans and other groups (Huxley 1867).
Hornbills are also unusual in possessing a unique ligament - the quadratomandibular ligament - that connects the body of the quadrate with the inside surface of the lower jaw. In ground hornbills the anatomy of the quadratomandibular ligament makes it impossible for the upper jaw to be raised or lowered without an automatic lowering or raising of the lower jaw, and the ligament is so strong that the lower jaw stays connected to the skull even in dried skeletons (Burton 1984). The hornbill quadratomandibular ligament was only discovered in 1940, and as Walter Bock noted in 1964 it has been mostly overlooked and little studied. Oh, if all this talk of 'raising or lowering the upper jaw' confuses you, I should explain that a special hinge zone at the base of the bill allows hornbills (and other birds with the same sort of hinge zone) to raise and lower the entire upper jaw relative to the rest of the skull, an ability termed prokinesis [adjacent sull of B. abyssinicus from Digimorph].
Given the importance of the bill tips in handling prey, it would make sense if the birds could see the end of their own bill, and indeed work on the visual field perceived by the birds indicates that the bill tips do indeed intrude into the lower part of the hornbill's binocular field. This is highly unusual among birds and it seems that the huge decurved bill and precision-grasping feeding technique that hornbills employ evolved in concert with their visual field (Martin & Coetzee 2004) [if you're really interested in this particular subject do check out Graham Martin's website]. Huge, stiff, flattened and widely spaced black eyelashes, the longest of which are 18 mm long, encircle the eye and overhang its upper part. The birds seem to use these as sunshades, deliberately positioning the head so that the cornea is shaded from bright light when appropriate (Martin & Coetzee 2004).
Several features of the hornbill head and neck seem specially suited to help support the big, heavy head. Ground hornbills have more cervical vertebrae than other hornbills (15 as opposed to 14) but, like other hornbills, their atlas and axis (the two vertebrae closest to the skull) are fused together. This is unique among birds, with the exception of one-off freaks. While most birds have just one occipital condyle, hornbills have two, as there is an accessory one on the supraoccipital (the bone that forms the upper border to the foramen magnum). Some of their neck muscles have special accessory slips that insert further down the cervical column than is typical for birds, and presumably this assists in carrying and moving the large head (Burton 1984). What's also odd about ground hornbill neck anatomy is that they have no cranial carotid arteries (Ottley 1879), and don't ask me how that works.
Casques!
What of course makes hornbills immediately distinct is the presence of the bony casque that sits on top of the bill. In ground hornbills this is a modest structure located dorsal to the proximal part of the bill, ramified internally by large spaces and sheathed in life by keratin (in the Northern ground hornbill the casque is much taller than that of the southern species). Basal hornbills, which probably include the ground hornbills (read on), have a small casque that is often little more than a mid-line dorsal ridge on the bill, but in more derived forms it is a large, mostly hollow structures supported internally by strut-like trabeculae (Kemp 1995): for images of sectioned casques go here. Casques probably function as identification devices as they differ in shape between species, sexes and growth stages, but an intriguing proposal is that they function as resonating devices used to amplify calls (Alexander et al. 1994).
In terms of casque morphology, the most strongly modified hornbill is the Helmeted hornbill Rhinoplax vigil, a territorial fig specialist of SE Asia. The casque of this species is almost solid, looks like a block of ivory - it's actually called hornbill ivory* - and, believe it or don't, is employed in aerial jousting (sectioned specimen shown here, photo by Matt Wedel). During this behaviour flying males smack their casques together, the resulting CLACK being audible from at least 100 m away (Kinnaird et al. 2003). The blunt leading edge of the casque might actually result from this head-butting behaviour.
* It's prized for carving by Chinese and Japanese artists, being used by the latter for netsuke sculptures.
Anyway, I digress. Compared to other hornbills, ground hornbills have elongate tarsometatarsi, and they also have short toes, though, strangely, with the hallux being the longest of the four (note that this is rarely depicted accurately in artwork). The scutes covering the tarsus look odd: large, non-imbricating scutes are scattered along the anterior surface like crazy paving, and not arranged in a row as is normally the case in birds with large tarsal scutes. Ground hornbills are reported to be able to run extremely quickly, apparently (I say again: apparently) at speeds of up to 30 km/h, and though they do their foraging by striding around on the ground, they're capable, though reluctant, fliers (see image below) [adjacent painting by Carel Brest van Kempen].
Family groups, strong bonds, long lives
Their social behaviour is interesting in that non-breeding individuals, including immatures of both sexes as well as adult males, assist breeding pairs in raising their young. As many as 12 non-breeders may collaborate to assist a single breeding pair. All of these birds are related and know each other well, and they use intimidation, play, mutual grooming and other forms of interaction to cement social bonds. It's well known that hornbill females become walled into a cavity nest while they incubate their eggs and raise their chicks, but ground hornbills are unique among the group in not doing this. Natural cavities in rocks or trees are used, and of the one-three eggs laid only one chick ever survives. The 'surplus' chicks may perhaps be an insurance should the first-hatched chick die. Apparently, no ground hornbill has ever been known to raise more than one chick, but if you look at the title of Kemp & Kemp (in press) below - a reference I borrowed from Alan Kemp's website - you'll see that some new data on this is soon to be published. Kemp is a leading expert on hornbills and has been involved in a long-term field study of ground hornbills.
Once chicks fledge, their mortality rates are low (31% survive to maturity), but they're tremendously slow in maturing, taking about six years. In keeping with this, ground hornbills are very slow breeders, fledging on average one chick every nine years. Pairs may go for as long as 18 years without breeding. Unsurprisingly, ground hornbills are highly vulnerable to human persecution and habitat loss, and because they rely on a few species of large trees for nesting (and, even then, require special trees that have natural cavities), the number of available nest sites may be a limiting factor on their distribution. As you would guess for all this K-strategy behaviour, they are long-lived: Kemp (1996) suggested that they might be among the longest-lived of birds, perhaps surviving into their fourth decade.
Avian pseudo-hominids
So in ground hornbills we seem to have slow-breeding, terrestrial, ground-feeding, carnivorous savannah-dwellers that belong to a clade of mostly arboreal, forest-dwelling frugivores. Kemp has noted that ground hornbills therefore seem to have followed a similar evolutionary path to us hominids (Kemp 1996). The complex social behaviour and apparent intelligence of the birds also makes them reminiscent of primates, though note that I don't want to promote the horrible opinion that the only time non-mammals become interesting is when they somehow seem mammalian in their behaviour or biology.
Phylogenetic studies indicate that ground hornbills are most closely related to the SE Asian Buceros hornbills, all of which are arboreal inhabitants of tropical forests (Kemp 1995, 2001). It is also fairly well agreed nowadays that Murie (1873) was right in arguing that hornbills are close allies of hoopoes and wood-hoopoes, the Upupiformes (Burton 1984, Olson 1985, Mayr 2000, 2003, Mayr et al. 2003). In fact some workers now use the term Upupiformes for this hornbill + hoopoe + wood-hoopoe clade (Mayr 2003). If you're more familiar with the inclusion of these birds within Coraciiformes - the name previously used for rollers, kingfishers, bee-eaters, todies, motmots, hoopoes and hornbills - then you'll be interested to know that there is now good evidence indicating that this grouping is artificial. More about that another time.
Anyway, this phylogenetic data indicates that the ancestors of ground hornbills were woodland or forest birds, and that the unusual behavioural characters of ground hornbills - the carnivory, the terrestriality, the striding gait (other hornbills hop when on the ground), the savannah habitat - are derived novelties. Indeed it's been suggested at times that the Bucorvus species are so unusual compared to other upupiforms that they should get their own 'family', Bucorvidae (Kemp 1995). This wasn't followed in the most recent review of the group however (Kemp 2001). What's more, we know that ground hornbills have been doing what they do for quite a long time, as fossil members of the group - B. brailloni and Euroceros bulgaricus - are known from the Miocene (Brunet 1971, Boev & Kovachev 2007). B. brailloni is from north of the Moroccan Atlas Mountains, and hence well north of where ground hornbills occur today, while Euroceros is from Bulgaria and hence shows that these birds once occurred in Europe. Various wing bone features suggest that Euroceros was a poor flier compared to Bucorvus: this might suggest that it was more strongly adapted for terrestrial walking (Boev & Kovachev 2007).
A few other alleged hornbill fossils have been reported from Eocene and Miocene Germany and France (Geiseloceros robustus, Cryptornis antiquus and Homalopus picoides) but Olson (1985) showed that none of them are really hornbills. Mayr (2007) showed that Geiseloceros is an ameghinornithid.
However, hornbills almost certainly originated in the Eocene at least, as we now know that close relatives of hoopoes had appeared by this time (Mayr 2000). We're simply missing the fossils [a toy cuddly ground hornbill shown here: more attractive and lovable than fossils].
Let's finish by saying that you don't need to compare ground hornbills with hominids or other primates, or with any other animals for that matter, to make them interesting. They're awesome, fascinating, complex birds.
Ground hornbills have been used on Tet Zoo before as analogues for a few other beasts: namely, azhdarchid pterosaurs and hypothetical big-brained post-Cretaceous maniraptorans. For more, see...
Refs - -
Alexander, G. D., Houston, D. C. & Campbell, M. 1994. A possible acoustic function for the casque structure in hornbills (Bucerotidae). Journal of Zoology 233, 57-67.
Boev, Z. & Kovachev, D. 2007. Euroceros bulgaricus gen. nov., sp. nov. from Hadzhidimovo (SW Bulgaria) (Late Miocene) - the first European record of hornbills (Aves: Coraciiformes). Geobios 40, 39-49.
Brunet, J. 1971. Oiseaux miocénes de Beni-Mellal (Maroc); un complement à leur etude. Notes et Mémoires Services Géoloques (Morocco) 31, 109-111.
Burton, P. J. K. 1984. Anatomy and evolution of the feeding apparatus in the avian orders Coraciiformes and Piciformes. Bulletin of the British Museum of Natural History (Zoology) 47, 331-443.
Huxley, T. H. 1867. On the classification of birds; and on the taxonomic value of the modification of certain of the cranial bones observable in that class. Proceedings of the Zoological Society of London 1867, 415-472.
Kemp, A. C. 1995. The Hornbills. Oxford University Press, Oxford.
- . 1996. Hammer of the savannah. BBC Wildlife 14 (5), 32-36.
- . 2001. Family Bucerotidae (Hornbills). In del Hoyo, J., Elliott, A. & Sargatal, J. (eds) Handbook of the Birds of the World, vol. 3. Lynx Edicions, Barcelona, pp. 436-523.
- . & Kemp, M. I. In press. How often might Southern ground hornbills fledge two chicks? Data from the Kruger National Park, 1967-1999. In Proceedings 4th International Hornbill Conference, Mabula Game Lodge, Bela Bela.
Kinnaird, M. F., Hadiprakarsa, Y.-Y. & Thiensongrusamee, P. 2003. Aerial jousting by Helmeted hornbills Rhinoplax vigil: observations from Indonesia and Thailand. Ibis 145, 506-508.
Martin, G. R. & Coetzee, H. C. 2004. Visual fields in hornbills: precision-grasping and sunshades. Ibis 146, 18-26.
Mayr, G. 2000. Tiny hoopoe-like birds from the Middle Eocene of Messel (Germany). The Auk 117, 964-970.
- . 2003. On the phylogenetic relationships of trogons (Aves, Trogonidae). Journal of Avian Biology 34, 81-88.
2007. Synonymy and actual affinities of the putative Middle Eocene "New World vulture" Eocathartes Lambrecht, 1935 and "hornbill" Geiseloceros Lambrecht, 1935 (Aves, Ameghinornithidae). Paläontologische Zeitschrift 81, 457-462.
- ., Manegold, A. & Johansson, U. S. 2003. Monophyletic groups within 'higher land birds' - comparison of morphological and molecular data. Journal of Zoological and Systematic Evolutionary Research 41, 233-248.
Murie, J. 1873. On the Upupidae and their relationships. Ibis 15, 181-211.
Olson, S. L. 1985. The fossil record of birds. In Avian Biology, Volume III, pp. 79-238.
Ottley, W. 1879. Bucorvus abyssinicus, on the vessels in its head and neck. Proceedings of the Zoological Society of London 1879, 461-467.
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Ah, vintage Tet Zoo. Some random comments...
A head-butting extant archosaur species? Wow!
It certainly wouldn't surprise me in the slightest if the traditional Coraciiformes turned out to be a wastebasket taxon. Hope you'll find the time to write more about this soon!
Given that ground hornbills apparently have had plenty of time to adapt to terrestrial living, I find it curious that they - like the majority of their forest-living relatives - have retained a mostly black plumage. One would think that they'd have evolved a more cryptic colouration in response to the presence of potential predators on the savanna. But then again, predation pressure doesn't seem to be a major problem to these birds, for some reason.
Hear, hear! (Now, if only people would also stop thinking that the only time non-human primates become interesting is when they somehow seem human in their behaviour or biology... But that's another story.)
Four subdivisions within the traditional Coraciiformes seem to be well-supported. There's the 'Upupiformes' mentioned by Darren, the 'Alcediniformes' (kingfishers, motmots, todies and bee-eaters), Coracioidea (rollers and ground-rollers) and Leptosomus (the Madagascan cuckoo-roller, which is just a bloody wierd-looking bird). According to Hackett et al., all four belong to the 'higher land-birds' clade, and if I remember correctly, all except Leptosomus form a clade with the Piciformes mixed in amongst them. It's still not impossible that the 'Alcediniformes' and Coracioidea, in particular, may form a monophyletic clade.
Thanks, Christopher. I only glanced through the Hackett et al. paper back when it was published last year; I'll have to look at it again. But didn't their results disagree with the traditional 'higher land-bird clade' concept?
Anybody ever noticed there seems to be a weevil named Leptosomus, L. acuminatus?
"But didn't their results disagree with the traditional 'higher land-bird clade' concept?"
They got a rather well supported clade of "land birds", but its contents don't entirely agree with the traditional concept. Caprimulgiforms and apodiforms don't belong to that clade (they're metavians), and neither are cuckoos and turacos (closer to core gruiforms etc.), however, "falconiforms" (polyphyletic) and seriemas (and parrots) are.
I'm a bit behind, but thought that Bucorvidae are the sister-group of Bucerotidae (other hormbills)?
Anyway, it is a prime group to humble you paleontologists!
Suppose a paleontologist would know hornbills only from fossils, with no live representatives.
He would look at the big casque and interpret it as a sign of polygamy or sexual competition. Nope, hornbills are sexually monogamous, even ones with helper individuals!
He would look at the fused neck vertebrae and deduce they would hit or peck into hard substrate. Nope, all are frugivores or insectivores!
I guess there would be several reconstructions of hornbills soaring over the sea, skimming for fish. ;)
BTW - curiously, what is the real purpose of these fused necks and casques?
"Anybody ever noticed there seems to be a weevil named Leptosomus, L. acuminatus?"
The generic name for the cuckoo-roller, Leptosomus Vieillot 1816 has priority over the weevil, which was named by Schoenherr in 1823. According to Nomenclator Zoologicus, there is a replacement name for the weevil, Rhadinosomus Schoenherr 1840.
Jerzy:
I don't know about that, but birds certainly may utilise rather unexpected food sources!
On phylogenetics:
Yes, ground hornbills are the sister group of other hornbills, and are no more closely related to Buceros than to any others. Sibley & Ahlquist (1990) is good enough to show that, and a mtDNA study by Michael Wink (still unpublished?) does so too. As does the nuclear data with the addition of a Buceros hornbill to the data set (also unpublished).
Usually, when hoopoes and hornbills are united the group is called Bucerotiformes, with Upupiformes being reserved for hoopoes alone.
And the monophyly of Coraciiformes as a reduced group lacking Bucerotiformes and Leptosomus, but including Coraciidae, is pretty secure based on nuclear DNA (Hackett et al. again). Traditional Coraciiformes is monophyletic if you submerge both Piciformes and Trogoniformes into it, which seems a shame to do.
They really are cool birds.
Sibley, C. G., and J. A. Ahlquist. 1990. Phylogeny and classification of birds. Yale U. Press, New Haven.
Hackett, S. J., R. T. Kimball, S. Reddy, R. C. K. Bowie, E. L. Braun, M. J. Braun, J. L. Chojnowski, W. A. Cox, K.-L. Han, J. Harshman, C. J. Huddleston, B. D. Marks, K. J. Miglia, W. A. Moore, F. H. Sheldon, D. W. Steadman, C. C. Witt, and T. Yuri. 2008. A phylogenomic study of birds reveals their evolutionary history. Science 320:1763-1768.
On "Higher Land Birds":
What traditional concept? Generally it's meant anything the author believes to be closely related to passerines. I also object to "higher", as if passerines were the pinnacle of avian evolution, toward which all other birds were aspiring. (It's obvious that stifftail ducks are the true pinnacle.)
"What traditional concept?"
I guess I meant "the last 9 or 10 orders in the traditional classification". Although you're right that there has never been a clearly defined concept of what the term "higher land-birds" meant.
On the suproccipital!?!?!
ZOMGZWTFBBQ!!!
And I thought I had seen it all when I understood Phlegethontia had lost the parietals. Incredible.
Colour me baffled.
<Nelson Muntz>Hhhhhaha!!!</Nelson Muntz>
Suck on it, beetle systematists! You won't get this dinosaur name!!!1!
As is Leptosomus.
"As is Leptosomus."
No, in Hackett et al. (2008) it was found to be the sister taxon to (trogons + "Coraciiformes"/Piciformes).
By the way, Alcediniformes was not found monophyletic in that study (even if, unlike Feduccia 1980, you don't include trogons). Coracioidea came out closer to (kingfishers + (todies+motmots)) than bee-eaters, but only with weak support.
Yep, so it seems that frugivory (and sealing of nest hole) are derived characters of larger forest-hornbills, which never occured in Bucorvus.
BTW, switch from insectivory to frugivory and larger body size in true hornbills would also mimic early primate evolution.
BTW2 - larger Aceros and Buceros hornbills, actually, eat a fair proportion of insects and small vertebrates. As some zoos learned, when they tried to put hornbills in mixed species exhibits and small birds and lizards started to disappear!
@Dartian
Ground hornbills are not much predated. I think black coloration, like in corvids, is more for group communication.
What beautiful eyelashes! BTW, what, exactly, are bird eyelashes made of? Are they feather filaments?
Gotta wonder if other long-snouted, bipedal Mesozoic dinosaurs followed a similar ecological path. I'm thinking specifically of unenlagiine dromaeosaurs. What's the EQ ratio for the ground hornbill? Can we even make brain size comparisons between modern birds and non-avian theropods to imply behavioral similarities?
A cluster uniting Upupiformes, Trogoniformes, Piciformes, Coraciiformes, Accipitriformes, Coliiformes and Strigiformes would have a plausible African origin. Maybe an avian analogous to mammalian Afrotheria. Perhaps in future, with more detailed phylogenies, we will call them "Afrornithes" or "Afraves".
@Zach- Yeah, looking at a ground hornbill skull, they don't seem that highly encephalized, esp. compared to mammals, but then again neither do african grey parrots. Birds just do things differently...
brain size comparisons maybe not, but brain structure comparisons could elucidate dromaeosaur behavior- a not uncommon endeavor for extinct animals
"A cluster uniting Upupiformes, Trogoniformes, Piciformes, Coraciiformes, Accipitriformes, Coliiformes and Strigiformes would have a plausible African origin."
I think stem group members of most or all of these are known from Europe/North America. An African origin of the clade is certainly not impossible, but I think we must be cautious in inferring the geographical origin of a group only based on the distribution of its extant representatives, especially if they can fly. Of course, I'm not saying that the clade necessarily originated in Laurasia either, as Europe/North America are simply studied more than most other parts of the world in that respect, and we have Messel, Geiseltal, and Green River but I think nothing comparable from the Paleocen/Eocene elsewhere.
Excellent post. Very informative. KUTGW.
Is it just me or do others think of something that might be formed into a patty, cooked on a grill and served between two buns with onions and catchup when you read the term: "ground hornbill"?
The stuffed hornbill also gave me recipe ideas.
Food on the brain. I must be getting hungry.
BTW, what, exactly, are bird eyelashes made of? Are they feather filaments?
Holy crap, good question! I assume that eyelashes in mammals and birds were independently acquired, which would be a great case of convergent evolution, but I've never read about it or even thought about it before. Do anyone know of any papers that discuss this?
Let's not get ahead of ourselves. The evidence for the existence of such a group is exceedingly weak, currently hard to distinguish from "none".
And I swear "Bucerotiformes" has priority.
Yes, bird "eyelashes" are feathers. According to the Prum & Brush theory, the original feather was an unbranched, hollow filament. Conceivably, they originated for a purpose something like vibrissae. (Some birds have vibrissae, by the way; they're feathers too.)
Thanks, John! I've always wondered what the heck bird "eyelashes" really were, and thought that this would be as good a place as any to ask about it. Now I wonder if maybe some non-avian theropods also could also have had them. Hmmm, maybe T. rex females attracted males by batting their pretty eyelashes!
Oops, hit "post" too soon by mistake. I meant to add this:
Is there anything stopping us from defining Aves as "all Saurischians closer to modern birds than to sauropodomorphs" - in other words, making all members of Theropoda (from Coelophysis to T. rex) into birds? And wouldn't it make perfect sense, considering their anatomy?
Hi Darren,
I've been following the Tet Zoo now for a little while, excellent site by the way.
Anyway, I just wanted to add that we have an outrageously tame Southern Hornbill at the Honolulu Zoo where I volunteer. He has been a fixture at the zoo since 1971 and is quite a character. I am still a bit amazed that, even as comfortable as he is around people, he has still managed to take a mate and be the dominant male in his little group.
#25:
No there's nothing stopping us from defining any group we like and attaching any name we like to it. But is it a good idea? I can think of several objections:
1. Do we need yet a third definition of Aves? Two are problem enough.
2. Wouldn't your name become a senior synonym of Theropoda, which therefore would no longer be a group under your classification?
3. This greatly changes the meaning of a familiar name. What's the countervailing benefit?
4. Why pick that particular branch, out of all the branches in the tree, to assign that name to? Sure, some avian characters arose near the base of Theropoda, but other characters arose earlier, and others later.
5. I've come to believe that crown-group definitions should be used in general for diverse, extant groups at least. The argument has been made capably elsewhere, so I won't go into it.
Also note that "bird" and "Aves" are not necessarily attached to each other. "Bird" isn't even part of the nomenclature. Under my preferred definitions, Archaeopteryx is a bird, but it doesn't belong to Aves.
Michael, if you include all theropods in "Aves" you may as well join the BAND. While it's ultimately an arbitrary definition, including Herrerasaurus in the same group as Corvus kind of ignores how wonderfully specialized and diverse BIRDS really are.
Under my proposed classification, Theropoda would be a junior synonom of Aves - so the name Theropoda would cease to exist. Now let's use an example. Coelophysoidea, which is the basalmost clade within Theropoda (I don't buy that hererrasaurs and Eoraptor are theropods) whould now be the basalmost clade within Aves. My own usage of "bird" is that a "bird" is anything that belongs to Aves. So under the usual classification, Archaeopteryx is not a member of Aves; therefore, It's not a "bird". So Theropoda would now be within Aves, and so members of Coelophysoidea would be very basal birds.
Is this a good idea? I think that it's a good idea because the anatomy of the whole of the Theropoda is overwhemingly similar to that of Aves. Pneumaticity, feathers (in the Coelurosauria at least), flexed legs, tridactyl feet, bipedal habits - all combined. Their anatomy is so much like a member of Aves' that if they were alive today, they'd probably be called birds, even with the teeth, tails, and claws.
However, I am aware that it cause some confusion. But in my mind Theropods as a whole are just to much like "birds" to not be placed within Aves. Of course, this is just more of a personal thing. Just keep in mind that I'm not actualy saying we should actually do this - now or even ever. It's just a suggestion, something to think about.
Zach: I just now saw your comment, or I would have included this in Comment 30. How is making T. rex a bird equivlent to joining the BAND? Birds (now including Theropoda under proposed definition) would still be dinosaurs. They always will be, John Ruben or no.
Including clearly non-avian theropods in Aves kind of diludes what makes birds special. Personally, I think Aves should be restricted to the crown group, which would alleviate confusion surrounding the exact placement of some more basal groups like deinonychosaurs, scansoriopterygians, and confuciusornids. I'm more accepting of placing the Enantiornithines with the crown group in Aves, but even then, the two groups differ pretty strongly.
Zach: I get your point now. And I'm really not suggesting that we actually do sink Theropoda into Aves; it was merely a suggestion based on their similar anatomy. I thought that perhaps it was a good idea, but an even better idea would be to leave everything as-is (although I still think that perhaps the deinonychosaurs belong Avialae.) Besides, I doubt that even I myself would be daft enough to go through with such a thing.
P.S. I would never, EVER join the BAND under any circomstance whatsoever. I don't care if Larry Martin tied me up and forced me to eat lima beans - I still wouldn't join.
Michael Erickson,
I didn't work my butt off to become a freakin' ornithologist!!
But seriously, moving Aves yet again solves nothing. It leaves either of the old Aves unlabeled and muddies up a perfectly acceptable named clade.
I agree that the future might well put deinonychosaurs closer to Aves than is Archaeopteryx, but that wouldn't make them members of Avialae (if we use the original definition, which was all taxa closer to modern birds than to Deinonychosauria).
Not that anyone seems to have noticed, but actually some parrots do seem to have a pretty noticeable encephalization judging by the very scientific method of looking at skulls in comparison. It is also possible that this is thrown off by relatively large jaws and eyes typically in birds, and a deceptively smallish body. But I stand by what I said about birds doing things differently, this is coming out in recent research that shows different parts of the brain do the same thing in especially clever birds and mammals- a rather interesting example of convergent evolution.
You forgot to add "...not that there's anything wrong with that." Unless you're trying to start a fight.
Paleogene theropods, by the way, strike me as under-studied, even compared to the amount of available material. Aside from the Messel, that is. Maybe you'd like to try your hand.
Thomas Holtz: Thank you for helping to clear things up. Now I want to tell you something: You are one of my all-time favorote paleontologists, and I am so humbled to simply be commenting on the same blog as you. You rock, Dr. Holtz. Seriously.
"I didn't work my butt off to become a freakin' ornithologist!!"
:-D :-D :-D :-D :-D
One of my favourite birds. Indeed they are up there in my top 10 in my lifelist (I only have Southern Ground Hornbill on my list, I still need to see Northern in habitat for a life tick).
Watching them forage on the ground made me think of two things:
(1) they resembled corvids in terms of behaviour way more than they resembled the other hornbills. Indeed when I see the local jackdaws feeding on the ground, it bears a strking similarity to the way the ground hornbills looked when feeding.
(2) As I think I mentioned in a comment to a previous post on this blog, I think that they may be a plausible model for how small dromaeosaurs behaved. Foraging in small groups on the ground for small vertebrates and large invertebrates.
Truly wonderful birds.
Many thanks to all for comments. In response to comment 9 from John Harshman...
I took the possible affinity between Bucorvus and Buceros from Kemp's writing: he strongly implies in some of his articles (e.g. Kemp 1996, p. 36) that the two are close. However, I agree that data now indicates that Bucorvus is more likely the sister-taxon to other hornbills.
On the use of the terms Bucerotiformes and Upupiformes, I suppose I was primarily following Burton (1984) and Mayr (2003): both used Upupiformes for the hornbill + hoopoe clade (p. 438 of Burton and p. 82 of Mayr). More recently, Mayr (2006) has used the name Bucerotes for the hornbill + hoopoe clade and has restricted Upupiformes to the hoopoes. As for nomenclatural priority, Bucerotiformes seems to have originated with Salvin & Hartert, 1892 whereas Upupiformes may not have originated until Verheyen used it in 1955: I took this from Sibley & Ahlquist, please correct if you know otherwise. Whatever, I agree that Bucerotiformes is clearly the older name. Bucerotes is Fürbringer, 1888, so I guess that's why Mayr and others (like Manegold and Livezey & Zusi) have taken to using it more recently.
Ref - - [see above for others]
Mayr, G. 2006. New specimens of the Eocene Messelirrisoridae (Aves: Bucerotes), with comments on the preservation of uropygial gland waxes in fossil birds from Messel and the phylogenetic affinities of Bucerotes. Paläontologische Zeitschrift 80, 390-405.
This can never work, because there are no gaps in the tree of life.
This is the exact same fallacy, applied in the opposite direction! :-)
I have to check if that's the original one... Gauthier himself (with various coauthors) changed it twice after all...
Ack! You're right!
Any idea as to the rate at which birds have evolved as apposed to mammals? I would think it would be much slower with the lack of predation land mammals have to put up with.
Since birds are dinosaurs, and dinosaurs are reptiles, why isn't "ornithology" just a side-branch of herpetology? It makes no sense.
And why isn't a herpetology just a branch of ichtyology? ;)
Jerzy: I don't get it. Reptiles and amphibians are not in the fish clade - so of course herpetology is seperate from ichthyology. But birds, being dinosaurs, are in the reptile clade - so ornithology should be included in herpetology.
Just as birds are "glorified reptiles", ornithologists are "glorified herpetologists." ;-)
Is there a "fish" clade?
How about the sarcopterygian clade?
Just because we have redefined Reptilia to include birds does NOT mean that we have to redefine "herpetology".
Owlmirror: I should have said fish clades, 'cause "fish" ain't monophyletic.
Sven DiMilo:
"Just because we have redefined Reptila to include birds does NOT mean that we have to redefine 'herpetology'".
I never said that we HAD too. I just thought: Since we've tossed birds into the Reptila, isn't it a bit odd to not just toss ornithology into herpetology? What would it hurt? Is it just because the ornithologists themselves don't want to be closely assotiated with people who study rattlesnakes and tiny frogs? If so, why does it matter what they think? I hope I'm not being rude to the ornithologists, but if they have hang-ups over birds being studied alongside lizards and alligators, it's their problem. Herpetology is "the study of amphibians and reptiles". Since birds are reptiles, why aren't they included? (Please keep in mind that I'm not trying to start an argument, a heated debate, or nothin' like that, I'm just dumping the contents of my brain.)
BTW, I would say this back on the actual post about semi-aquatic theropods, but there ain't no action left over there. Didn't Barsbold (1981) suggest that the odd little hands of Ingenia were webbed for swimming?
Fields of study are defined by the people in them. Biologists study living things, and define what's alive according to whether they're interested in it. Herpetologists are interested in herpetology, ornithologists in ornithology, chemists in chemistry, ad repletum. If they're not interested in it, it's not part of their field, full stop. If you want to redefine ornithology, you have no choice but to get the next generation of ornithologists on your train.
The only time this causes any trouble is when the fundamental phenomena of a field turn out to be, for whatever reason, abhorrent to its practitioners. Astronomers, as a group, utterly detest plasma fluid dynamics, apparently because it doesn't have nice mathematical properties and might enmesh them in lab work or unpleasantly large computer simulations. Their solution, thus far, has been to avoid seeing plasma fluid phenomena, and to invent all kinds of crazy stuff instead. Maybe it will doom their field, but not for a while, and anyway people will still pay for the telescopes.
Now, you might say something similar has happened to the BANDy ornithologists, and you might be right if any non-birdy theropods had survived. What has happened instead is that there are no longer any paleo-ornithologists; that field just evaporated.
I am interested in this analogy hominids/hornbills. I am preparing a paper on this kind of analogies for a historical journal. Most analogies were very superficial from a evolutionary point of view (analogies between horses or kangaroos and primeval man etc.).
I would like very much to read Kemp's paper published in BBC Wildlife, but I am not able to find it online. Does somebody have a PDF?
Thanks,
Renato
Each gene has its own evolutionary rate along each internode. Global statements like what you seem to want are not possible.
No.
Unless you want to restrict "fish" to Actinopterygii, which would be a good idea and would change almost nothing -- but nobody has seriously advocated it yet.
Speak for yourself (and Gauthier & gang). I think this was a very bad idea. Ceterum censeo reptilia esse delenda.
I think he did, but I don't know why (haven't seen the paper), and the arms are way too short for that anyway.
Please explain.
J. Clarke, S. Hope, G. Mayr, Hou L., Zhou Z., Zhang F.? And that Czech guy whose name I forgot? There are still vertebrate paleontologists who are pretty narrowly specialized in fossil birds.
(Hou Lianhai is remarkable for switching from BAND to BAD, if his coauthors and various implications in those coauthored papers are an indication.)
I suspect you mean Andrzej Elzanowski, who is Polish. How about G. Dyke, P. Houde, D. Steadman, H. James, and those BAND guys, who, whatever else they may be, are paleornithologists too. Now there is a fair divide between those who study mainly Neornithes, mainly Cenozoic, and those who study mainly stemmy-birds, mainly Mesozoic. Still, there aren't many of them compared to the amount of material.
Herpetology: If you subsume ornithology, don't you have to subsume mammalogy too? Herps are massively paraphyletic. And isn't herpetology just a subset of ichthyology? Bunch of weird, landliving sarcopts, really. Birds, on the other hand, are a perfectly good clade.
Largely, these sciences are organized based on where and how you find and study your beasties. Herpetologists look down. Ornithologists look up. Herps hide. Birds do their thing where you can see them. Herpetologists collect pickles. Ornithologists collect skins. Etc.
I'm guessing David meant JiÅà MlÃkovský (who is Czech, but a little on the outer with other palaeornithologists).
As John said, the separation between disciplines is largely a matter of favoured methods, as well as a good dose of historical contingency. To give an example a little closer to home for myself, mites are technically arachnids (and well-nested within arachnids), but acarology has usually been treated as a separate discipline from arachnology.
Does anyone know where I can find Barsbold's (1981) Ingenia paper? Thanks.
Herps study extant cold-blooded tetrapods, let's put it that way. Ornithologists study extant avian archosaurs, and vets charge you way too much to look at your leopard gecko for five minutes.
I know it, Zach. I've thankfully never had to take my leopard gecko to the vet. However, we once had to pay over 300 smackers for the vet to look at a baby turtle we had - we told her it wouldn't eat, and she suggested we feed it*. It died two days later.
*What the @&$# ?
well, except for excluding all of the chondrichthyans, of course...
Sauropsida, then. Doesn't change my point about the science of "herpetology" excluding birds.
Let's not..."ectothermic," please.
Yes, fine, ecotothermic.
Zach Miller - did you see my own vet story?
David Marjanovic - If you're interested in seeing Barsbold's Ingenia paper, I just found it at the Theropod Archives.
No, I meant MlÃkovský, who published a humongous book on the fossil Cenozoic birds of Europe... classified by nothing but brain anatomy, so basically you can't find anything in it.
Elżanowski is not quite that specialized, though he gets close. Good point, however, about Dyke, Houde and Steadman (I don't remember James at the moment).
Yes. There aren't that many of those, at least not when compared to the 25,000-upward teleosts.
(Besides... have you eaten ray wing? It's not fish. It's... fibrous and slimy at the same time. Deeply bizarre.)
Oh, thanks, I'll check it out as soon as I find some time (maybe next week).
You're welcome, David. BTW, it's not the 1981 paper where Barsbold suggests webbed hands for Igenia, it's the 1983 fallow-up, which (thankfully) is also at the Theropod Archives. I've been looking through that site all day - all sorts of goodies there!
Yeah, saw your story, Mike. That's basically what my vet told me. "He has to eat!" "But he doesn't have an appetite and actually turns his head away from food." "Use an eyedropper with baby food!"
*does this for three days*
*lizard dies*
Thanks!
I know it, Zach. My conversation with the vet went something like this: "He won't eat anything!" "Why don't you feed him something." "We have, he won't eat it!" "Try mealworms instead of turtle food sticks." "We have, he won't eat ANYTHING!" "You should give him food, or he'll starve." "HE WON'T EAT!" "Feed him." We paid her 300 $ for that bull crap, and the turtle didn't even make it!
Oh yeah, does anybody know where I can find the Bakker et al. (1992) Edmarka paper?
Yeah, by the time your ectothermic pet stops eating, there's just not a whole lot you can do. This comes from years and years of raising lizards. Happened with my anoles, happened with my chameleon, happens with leopards. I'm giving one of my lizards (Liquid) baby food right now, and he's not thrilled about it, but he's also losing weight quickly. I don't think he's gonna make it, but dammit I can TRY.
Also, don't worry about Edmarka. All signs point to it being a junior synonym of Torvosaurus. Similar situation with Creosaurus (=Allosaurus).
Well, this is a zoology blog... suffice to say condensed-matter physicists wouldn't get away with making up dark matter when their present theories failed to account for observations.
I suppose late bird evolution does offer scope for serious work.
Helen James, at the Smithsonian? Big name in (mostly Quaternary) avian paleo.
Zach Miller: Yeah, I know that Edmarka is probably just a specimen of Torvosaurus - but I'm still interested in reading the paper. And I don't think that Creosaurus is a distinct genus; however, I *do* think that it's a distinct species from Allosaurus fragilis. The skulls are way too different for them to be the same species. Idividuals within a species just don't vary THAT much (unless human breeding is involved, such is the case with Canis familiaris.
Zach Miller: Oh yeah, I forgot - I sincerly hope that Liquid pulls through. I'm a sensitive guy who loves animals and has herps of my own, and I know all too well what it's like to atempt to care for a pet in the vain hope that it just might make it.
Anybody: What's going on with that Procompsognathus skull? I've heard that some beleive it's actually a non-dinosaur, while others hold on to it's dinosaurian status. I've seen it illustrated in Gerhard Heilmann's old The Origin of Birds, and it does look theropodian to me. Does anybody know what's up, and what's the most likley identification?
It's the sarcopterygians that are the problem...
Come ooooon.
http://en.wikipedia.org/wiki/Bullet_Cluster
http://en.wikipedia.org/wiki/MACS_J0025.4-1222
What's not to like?
Depends on your species concept du jour.
Last time I checked, it was considered a "sphenosuchian", but that was long ago...
Did Heilmann present a specimen drawing or just a reconstruction?
Speaking as a proud sarcopterygian myself, I resent that implication.
David Marjanovic: Heilmann presented a beautiful, rasther large pen-and-ink specimen drawing of the skull. To me it looks like a theropod that's convergent with "sphenosuchians", rather than a "sphenosuchian" convergent with theropods.
*Points to preceding comment* I hate spammers.
What's not to like?
This is a zoology blog, so I'll only mention that X-ray emitting stuff is necessarily fully-ionized plasma, not gas, and that if you start out assuming that only gravitation can account for motion, you will find yourself inventing undetectable mass when what's there doesn't. But they're good pictures, and that's what really matters.
"HE WON'T EAT!"
Mine had at least sense to show me how to open the turtle's mouth by force. You press the sides.
In any case, you need to find a vet who specializes in reptiles. Reptile forums would point to one.
PS. if you tell an ornithologist that you are a herpetologist, he would probably answer "nice, this pressing flowers between sheets of paper".
:P
Aah, glad to see this discussion is still 'active' (thread drift notwithstanding)!
Following the links from this topic has led to numerous references to Nemo Ramjet (and even comments on this blog, as recently as last year, by Mr. Ramjet himself), yet frustratingly, all links to his site come up as 404. Does anyone know if his data is preserved elsewhere?
As a proud 'speculative-biology' geek, SF fan (yes, including Barlowe from WAY back), and amateur paleoartist (e.g. recent issues of Prehistoric Times) creating and using 3D digital content, I would be fascinated to see some of the Nemo Ramjet work.
Can anyone provide a relevant active URL, or enlighten me as to why the Nemo Ramjet site is defunct?
Much obliged!
John Harshman wrote:
No there not. They are polyphyletic. They include amphibians, but not mammals; reptiles, but no birds. I think it might be the only organismal science that retains that typological base.
Sven DiMilo wrote:
I'm with David. Redefining Reptilia to incorporate those overly "glorified reptiles" was an incredibly bad idea, and is partly responsible for some of the massive resistance to phylogenetic nomenclature.
Screw that. Bradymetabolic FTW. :)
Just to elaborate on this a bit more, I mean to say that herps are polyphyletic because they include amphibians, and reptiles, but none of the groups that link amphibians and reptiles. It is essentially, a random grouping of critters.
What are these groups that link amphibians and reptiles? Are you talking about diadectomorphs, or some such? Classically speaking, amphibians are paraphyletic, because they include all tetrapods that aren't amniotes. Now, if you restrict Amphibia to lissamphibians, I take your point. But herptetologists don't commonly use such a definition, or think about it at all. Unless we consider the group membership of extinct groups, and exclude the common ancestor of all herps from the group, herps can be considered paraphyletic.
And they're hardly random, either. In terms of modern taxa, they're what you have left when you remove birds and mammals from Tetrapoda.
"Redefining Reptilia to incorporate (birds) was an incredibly bad idea."
No, it wasn't. Dinosaurs are reptiles. If birds are dinosaurs, they are by default reptiles. "Birds belong to a clade within Reptila (Dinosauria) but birds do not belong to Reptilia." WTF?
Also, all we have to do is LOOK at the anatomy of birds to see that not only are they reptiles, they are not that "glorified". Look at their scaly, bony feet. Their reptilian-type eggs. The distinctly lizard-like face of the Sula leucogaster. The fact that many bird beaks are made up of seperate keratin peices that resemble the facial scales of reptiles. The fact that pythons brood their eggs like birds. The fact that the development of the lenses of the eye are identical in reptiles and birds. The fact that the brain of the bird, in all its main features, is exactly the same as that of a reptile. The fact that the male genitalia, in its entire development, of reptiles and birds is identical. Must I go on? I can give you more if that's not enough. And please don't ask for references - It would take me hours to list everything. Gerhard Heilmann (in The Origin of Birds) gives a beautiful overview of how similar birds and reptiles really are. Despite being incredibly outdated in some places, the sections in the book concerning this discussion are quite up-to-date.
That's the problem right there. Because synapsids are now considered removed from Reptilia, there is a whole group of animals that get excluded from the term. This includes the ancestor of reptiles (as the MRCA of reptiles and Mammals gets removed). Thus creating the polyphyly.
Sory if that I sounded like a raving lunitic on comment 82. All I really want to say is that including birds in the Reptilia is not a bad idea at all when you consider their anatomy, embryonic devolpment and phylogenetic position as theropod dinosaurs.
"Undetectable"? Gravitation lensing! That's how the dark matter was detected in the two galaxy collisions I linked to!
Or to their total group (that is, all temnospondyls, or all lepospondyls except probably the adelogyrinids, depending on the phylogenetic hypothesis). Indeed, a chapter with this definition for Amphibia has been submitted for the PhyloCode companion volume.
See, that's what I take issue with. In this respect, I'm a greater Bakker fan than you. ;-)
Really, the term should be abandoned altogether. It's only misleading in several respects.
Fixed it for you :^)
See? That's what I mean by misleading.
On the one hand, they are amniote eggs, of the type also found in monotremes. On the other, they are archosaur and specifically dinosaur eggs (hard shell). I'm not aware of any egg-related autapomorphies of Sauropsida.
I've read Goodrich 1916, the paper where Theropsida is coined and Sauropsida is used for the first time after Huxley introduced it (in a much vaguer sense). It's amazingly close to phylogenetic nomenclature. Theropsida and Sauropsida almost explicitly get branch-based definitions.
This ancestor gets removed? Why? How?
There seems to be a lot of confusion here. Michael wants to call birds (but not mammals) "reptiles" on the basis of a bunch of amniote symplesiomorphies. Dude, that's advocating for paraphyly.
The distaste for adding birds to Reptilia is not a desire to avoid cladistic classification, but a desire to avoid confusion about the meanings of old names. Sauropsida yes, Reptilia no. Reptilia is paraphyletic, and no longer a formal taxon name. Similarly, "reptile" is a term that applies to no taxon, but that might conceivably be as useful as "tree" or "worm". Would you attempt to redefine the classical taxon Vermes and apply it to some real group?
As for herpetology, haven't you notice that adding birds doesn't make the subject matter monophyletic, under any name, unless you exclude amphibians or include all tetrapods?
David Marjanovic and Josh Harshman: Okay okay, I get it! Herpetology stays the same! Ditch Reptila, Sauropsida Sauropsida Sauropsida! Thank you for your responses, I get it now.
Oddly enough, my Field Museum ID badge says "Josh" too, so the error seems oddly common. Is this some kind of confusion with Josh Hartnett?
I my case, it was a simple typo. I don't know what's going on with the others.
David: Collisions? Who demonstrated that those were collisions? (Yes, grav lensing is very cool.)
Now that "Reptile" is retired, we need only retire "Dinosaur" and all manner of upsets vanish. With "Dinosaur" retired, reporters, childrens' book authors, and horror-movie writers will be free to call nessies, azhdarchids, and latter-day fascist-libertarians "dinosaurs" without fear of excoriation, just as they can now call them all "reptiles".
What else? The parts are still moving -- at the expected velocities.
Most importantly, there's something invisible out there that does a lot of grav lensing.
"What else?" Indeed, I see what you mean: for an astronomer there's nothing out there but collisions. How do you suppose, by the way, that they measure transverse velocity? It's one thing to deduce a pile of non-radiating mass somewhere, and entirely another to assert it's made out of magic particles, and yet a third to insist that there's way more of them than hadrons. But this is a zoology blog.
So, getting back on topic... according to the species concepts used on bears, giraffes, and canids, isn't (or wasn't, until recently) H. sap. two or more species? And does it make biologists nervous to treat environmental details as part of what makes a population one species or two?
Nathan, I've been meaning to write a blog post about that very topic for a long time (under my "Potentially Inappropriate Posts" banner). According to the subspecies concept (for which geographically isolated, occassionally morphologically distinct populations of a species get their own subspecies name), I would argue that humans should be split into three or more subspecies. It's not a can of worms I'm comfortable opening, but it's often on my mind.
Zach: It seems clear that whatever was the case in the 19th or 15th century, humanity is all of one species now.
Whatever may be uncomfortable about our having been two or more distinct species up until a century or five ago might reasonably bother biologists, many of whom must prefer to think of a species designation as an Platonic ideal referrable only to the genetic lineage. I.e, we may have splittings, mergings, and reassignments, but before those events we were wrong, and now we're closer to right. That we could go from three species to one without acknowledging a mistake, and without tracking an actual change to the set of genes in the population, must bother lots of old-timers.
Redshift?
If it weren't "magic", we could see it in the infrared or something. And did you forget about the fact that galaxies move like wheels, not like whirls?
I don't know what these are; and the important part is that the systematists working on those groups don't know it either. It's really rare to see a paper that's explicit on which species concept it uses. (The ICZN doesn't even mention the problem -- taxonomic freedom, I suppose.)
Would surprise me, because there is one human population (with gene flow across the Bering Strait), and all morphological and genetic variation among humans is clinal.
500 years ago, the populations of Easter Island and probably Tasmania were also isolated, but that hadn't been enough for any consistent morphological or even genetic differences to emerge as far as I'm aware. (That said, of course, there's not much left of the aboriginal Tasmanians.) It might, however, still count for the Phylogenetic Species Concept and the like. In that case, we've had species fusion according to those concepts.
Why? Human variation is clinal. Go from Turkey to China, and people become gradually more Chinese-looking; there's no place a line could be drawn (...and, BTW, people from one end to the other speak very closely related Non-Chuvash-Turkic languages). Go from Yemen to the More or Less Democratic Republic of Congo, and people become gradually more Congolese-looking; again there's no place a line could be drawn. I know people from Rwanda with skin the color of chocolate with 50 % cocoa, but completely European noses.
Yes, that's the conclusion I would've ultimately drawn in the post, though I also wonder if, at some point in the not-too-distant past, when human settlements were fewer in between and more regionally isolated, a subspecies concept could be implimented across humanity. Just a curiosity.
David: Red shift only tells you about recessional speed, unless you can get some light reflected from something else; that only works nearby. Transverse velocity is usually just assumed. Galactic rotation is still interesting.
But on-topic... H.<?i> populations were split across the Bering strait for, what, 14 ky? How much mixing was there across the Wallace line from 20 kya until the Malay got around? (It might have been a good thing for descendants of those Australians and Americans that most of the Eurasian adaptations after the respective splits were net harmful -- except that the harm caught up with them anyway.)
[sorry, that got cut off.] ... H. populations were split across the Bering strait for, what, 14 ky? How much mixing was there across the Wallace line from 20 kya until the Malay got around? (It might have been a good thing for descendants of those Australians and Americans that most of the Eurasian adaptations after the respective splits were net harmful -- except that the harm caught up with them anyway.)
Oh, and hadrons are perfectly capable of not radiating.
Of course, but do we see both clusters exactly at a right angle?
Definitely not, no. There were at the very least three migrations across it within that time, and perhaps one from Europe (along the Atlantic sea ice margin) even earlier, and then there are those incredibly old sites in Chile...
Anyway: the Na-Dené languages are apparently the sister-group of the Yeniseian languages, and the ancestors of their speakers crossed the Bering Strait less than 10,000 years ago; the ancestors of the speakers of the Eskimo-Aleut languages arrived even later, and some have even stayed at the eastern end of the Chukchi Peninsula. And that's just the contacts we know of, because they've left traces that are hard to overlook.
No idea, but probably more than none.
What do you mean?
If they have the temperature of the vacuum, and if they receive no radiation whatsoever, then yes. I wonder if an extremely thin gas is compatible with the calculable density of the gravitation lens; and I don't think it would just ignore a collision the way those lenses are apparently doing.
> H. populations were split across the Bering strait for,
> what, 14 ky?
The Chukchi raided the west coast of NA with virtual impunity for several hundreds, if not thousands, of years, see here:
http://www.romanarmytalk.com/rat/viewtopic.php?t=10330&start=20
and scroll down (warning: if you scroll down too much, things will get rather weird. Some take reenacting a little bit too far ;-). Nice chalicothere tattoo, though).
> How much mixing was there across the Wallace line from 20
> kya until the Malay got around?
Dravidian influence on indigenous Australian customs and languages has been suggested.
Sorry, off-topic: "do we see both clusters exactly at a right angle?" Doesn't matter, if you can't measure the precise angle. E.g., 91°, they're approaching one another, 89° they're receding from one another. 88°, one speed, 89° twice as fast. "I wonder if an extremely thin gas is compatible with the calculable density of the gravitation lens; and I don't think it would just ignore a collision..." Plenty of thin gas -- plasma, really -- lies between us and them, not radiating, curiously, nor protected from radiation, and manifestly transparent. And, again, no collision has been demonstrated, just assumed.
But back on topic... I thought the Chukchi attacks had been shown to be recent, i.e. post-medieval. Anyway, would the arrival of a few dozen specimens at 3 ky intervals qualify as mixing? Probably the Hawaiian nene got more admixture.
I wonder if Dravidian influence on Australians is better supported than that of Polynesian language on islanders off California.
The Chukchi-Kamchadal languages are neither Eskimo-Aleut (though probably fairly closely related) nor Yeniseian. That's not what I was talking about.
Are you talking about the fact that the Dravidian languages are remarkably similar to the Australian ones in some features of their sound systems (but in apparently nothing else, including the rest of the sound system)?
How do we know about it then?
The ISM and the IGM (interstellar medium and intergalactic medium) are mostly partially ionized H. They're transparent at most wavelengths, but we can't see far where they're not. If those masses are ISM, they're necessarily invisible to us. They could, instead, be clouds of fairies, assuming fairies have mass, or WIMPs if we earnestly wish it.
... Or (resolutely returning to topic) ropens.
> Are you talking about the fact that the Dravidian languages
> are remarkably similar to the Australian ones in some
> features of their sound systems (but in apparently nothing
> else, including the rest of the sound system)?
This, and the (alleged?) similarity of kinship systems.
You would love this hornbill picture:
http://www.zoochat.com/192/hornbill-93605/
wooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooow