Tag Archives: Comparative Biology

The Otter Civet

From the Museum of Comparative Zoology (Harvard)

Otter Civets (Cynogale bennettii) are a poorly known and endangered species of hemigaline viverrid from the Thai-Malay Peninsula, Borneo and Sumatra (Veron et al. 2006). There are also unconfirmed reports from northern Vietnam (“C. lowei“), southern China, northern Thailand and Java (Veron et al. 2006). The mount above appears to be this specimen, and was probably collected in Borneo in 1881 by Henry A. Ward. It certainly shows its age, but it’s no taxidermic aberration — photographs of live specimens show the whiskers and mystacial pads really are that ridiculously hypertrophied.

The illustration above demonstrates more remarkable morphology — the nostrils open dorsally, an even more extreme position than those of seals* and otters (Pocock 1915). Pocock (1915) speculated this feature allows Otter Civets to be ambush predators, picking off unsuspecting birds and small mammals looking for a drink. Nowak (2005) lists birds and small mammals as part of the Otter Civet’s diet and treats Pocock’s speculative behavior as likely, although it still appears to be entirely hypothetical. Any nature documentarians up for filming this potential mammalian mini-crocodile in action? Anyways, Otter Civets also have adaptations for activities below the surface as their nostrils can be closed with flaps, and their ears can be closed as well (Nowak 2005). While some early workers considered Otter Civets to have large orbits (Gregory & Hellman 1939), the eyes appear to be on the small side for a civet, which is unsurprising considering the vast array of whiskers.

* But not Leopard Seals, it would seem.

Viverrids... and prionodontid... on parade!

Top Row: Banded Linsang, Masked Palm Civet
Bottom Row: Binturong, Common Palm Civet, and Otter Civet.

Otter Civet weirdness doesn’t stop at the head. Despite their closest relatives being plantigrade, Otter Civets are fully digitigrade (Gaubert et al. 2005), which is rather unexpected for a semi-aquatic species. The feet are broad with flexible digits and some webbing (Nowak 2005). The tail is curiously short (compare to the civets… and prionodontid… above) and lacks specialized musculature (Nowak 2005). Due to the lack of webbing and underwhelming tail, Nowak (2005) speculated that Otter Civets are slow and unmaneuverable swimmers specialized for capturing cornered prey, which ties in with Pocock’s speculation that the abundant whiskers are an adaptation for discovering hiding prey. Aside from terrestrial species, their diet includes fish, crustaceans and possibly molluscs (Nowak 2005).

Top Row: Otter Civet, Aquatic Genet
Bottom Row: Hemigalus, Chrotogale
All skulls from Gregory & Hellman (1939).

Otter Civets are members of the clade Hemigalinae, along with Hemigalus, Chrotogale, Diplogale and, it was recently argued, Macrogalidia (Wilting & Fickel 2012). The skeletal comparisons above and below also include the Aquatic Genet (Genetta piscivora), a more distant relative that, as the name suggests, is also semi-aquatic. Gregory and Hellman (1939) discussed some minor skeletal traits shared by Otter Civets and Aquatic Genets but found the convergence to be minor. Otter Civet teeth really stand out: the elongate, serrated premolars are specialized for grasping prey while the blunt-cusped, rounded molars are specialized for crushing (Gregory & Hellman 1939; Nowak 2005). Gregory and Hellman (1939) also described an enlarged infra-orbital foramen and enlarged areas for muscle attachment anterior to the orbits which is related to the abundant whiskers and hypertrophied facial musculature, although it’s far less pronounced than what I would have expected. Curiously, there doesn’t seem to be any obvious anatomy relating to the strange position of the nostrils.

Top to bottom: Otter Civet, Aquatic Genet, Hemigalus
Skulls from Gregory and Hellman (1939).

Otter Civets have been kept in captivity and have apparently been observed foraging in water (Vernon et al. 2006), although, full disclosure, I cannot find any specific information on its behavior in water. On land it has been observed doing some surprising things — climbing trees, as well as eating fruit and insects (Nowak 2005; Wilting et al. 2010) — although most observations appear to be fleeting glimpses. Otter Civets are typically photographed nears ponds and streams and are thought to primarily inhabit peat-swamp and primary forests, although they have also been observed in logged and secondary forest (Wilting et al. 2010, Cheyne et al. 2010). However, observations of Otter Civets are becoming increasingly uncommon and it is believed habitat destruction has reduced its population (Veron et al. 2006).

And on a somewhat more upbeat note, here is some of the first footage of Otter Civets in the wild:

References:

Cheyne, S. et al. (2010) First Otter Civet Cynogale bennettii photographed in Sabangau Peat-swamp Forest, Indonesian Borneo. Small Carnivore Conservation 42 25–26. Available

Gaubert, P., et al. (2005) Mosaics of Convergences and Noise in Morphological Phylogenies: What’s in a Viverrid-Like Carnivoran? Systematic Biology 54(6) 865–894. Available

Gregory, W. & Hellman, M. (1939) On the evolution and classification of the civets (Viverridae) and allied fossil and recent Carnivora: A phylogenetic study of the skull and dentition. Proceedings of the American Philosophical Society 81 309–392. Available

Nowak, R. (2005) Walker’s Carnivores of the World.

Pocock, R. (1915) On some of the external characters of Cynogale bennettii Gray. Proceedings of the Zoological Society of London 15(88) 350–360. DOI:10.1080/00222931508693650

Veron, G. et al. (2006) A reassessment of the distribution and taxonomy of the Endangered otter civet Cynogale bennettii (Carnivora: Viverridae) of South-east Asia. Oryx 40(1) 42–49. DOI: http://dx.doi.org/10.1017/S0030605306000068

Wilting, A. & Fickel, J. (2012) Phylogenetic relationship of two threatened endemic viverrids from the Sunda Islands, Hose’s civet and Sulawesi civet. Journal of Zoology 288(3), 184—190. DOI: 10.1111/j.1469-7998.2012.00939.x

Wilting, A. et al. (2010) Diversity of Bornean viverrids and other small carnivores in Deramakot Forest Reserve, Sabah. Malaysia.Small Carnivore Conservation 42 10–13. Available

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Cutting off the Trunk to Spite the Whale

A new look for Makaracetus bidens

In Trunks, Proboscides & Makaracetus, I argued the extinct whale Makaracetus bidens probably didn’t have a “trunk” or “proboscis”, contra Gingerich et al. (2005). For one thing, an overhaul of terminology resulted in ‘trunk’ no longer referring to a nasal appendage, ‘proboscis’ being restricted to tubular nasal/lip structures capable of grasping food, and all other elongate nasal structures being termed ‘prorhiscis’ (Milewski & Dierenfeld 2013). Makaracetus certainly had over-developed facial features compared to its cetaceous relatives, but it didn’t appear any more likely to have a “trunk” than, say, a camel.

Boar skull, courtesy of Markus Bühler.

One feature of Makaracetus I didn’t discuss in the last round were its maxillary fossae, which Gingerich et al. noted were also present in pigs. This feature is plainly visible on the boar skull above — it’s the virtual trench running from the orbits down the snout. These fossae provide attachment for the maxillolabialis superior and inferior, which are responsible for moving the protruding snout (Gregory 1920).

PiggyNoses

Pig snout musculature. From Gregory (1920)

What’s interesting is that pigs almost fit the definition of having a proboscis. Pigs can apparently grasp food items with both their nose and lip musculature, but fall short of the definition since only the disc is mobile (Milewski & Dierenfeld 2013). Does this mean Makaracetus may have had some sort of proboscis after all? Probably not. It’s notable that one trait shared by proboscides owners is directional olfaction (Milewski & Dierenfeld 2013), which seems like an unlikely trait for a cetacean to evolve, considering they lack the ability to smell underwater. Furthermore, pigs don’t have exclusive rights to maxillary fossae.

Top: Makaracetus from Gingerich et al. (2005)
Middle: Potamochoerus sp. from Gregory (1920)
Bottom: Macropus sp. from Gregory (1920)

Kangaroo maxillary fossae bear a surprising resemblance to those of Makaracetus — they’re similar in extent, only present anterior of the antorbital foramen, and are on the lower half of the rostrum. Unlike pigs, the maxillary fossae of kangaroos provide an origin for part of the buccinator muscle (Gregory 1920). The fossae are also present in baboons, where I suspect they have something to do with this display. Maxillary fossae also appear to be present in llamas but apparently not camels, for some reason. Considering the apparently variable functions of maxillary fossae and the additional premaxillary fossae of even more mysterious purpose, I’d agree with Gingerich et al.’s interpretation of “hypertrophied facial muscles” for Makaracetus and hesitate to speculate much further.

So if the nose of Makaracetus didn’t bear a proboscis or prorhiscis, what did it do? Perhaps the expanded nasal vestibule was merely a side effect of the snout warping into a down-turned shape. Another parallel could be found in Gray Seals, which have nasals retracted to a similar degree as Makaracetus and enlarged noses which function as displays (Miller & Boness 1979); however more specimens will be required to conclude that the trait was sexually dimorphic. Milewski & Dierenfeld (2013) hypothesized that the enlarged nose of Moose may act as a buoy to counterbalance to forelimbs when foraging underwater, a trait which could be beneficial to the apparently benthic-feeding Makaracetus. However, Makaracetus appears to have a much smaller nasal chamber than Moose, so the potential benefits could have been minimal.

I reconstructed Makaracetus as a Hippo/Manatee/Walrus-thing up top, but I suspect my endeavors were far too conservative. Makaracetus was a beast without obvious parallels and its true appearance can probably never be known. Still, there’s no reason to go slapping a “trunk” on strange-looking skulls, and I hope Milewski & Dierenfeld (2013) will get the attention it deserves and open minds to the myriad other possibilities of big, weird noses.

References:

Gingerich, P. et al. (2005) Makaracetus bidens, a New Protocetid Archaeocete (Mammalia, Cetacea) from the Early Middle Eocene of Balochistan (Pakistan). Contributions from the Museum of Paleontology 31(9) 197—210. Available

Gregory, W. (1920) Studies in comparative myology and osteology, No. V. — On the anatomy of the pre-orbital fossæ of Equidæ and other ungulates. Bulletin of the American Museum of Natural History 42 265—283. Available

Milewski, A. & Dierenfeld, E. (2013) A structural and functional comparison of the proboscis between tapirs and other extant and extinct vertebrates. Integrative Zoology doi: 10.1111/j.1749-4877.2012.00315.x

Miller, E. & Boness, D. (1979) Remarks on display functions of the snout of the grey seal, Halichoerus grypus (Fab.), with comparative notes. Canadian Journal of Zoology 57 140—148. Available

Trunks, Proboscides & Makaracetus

The terms ‘trunk’ and ‘proboscis’ have been applied to a heterogeneous array of bits danging off vertebrate faces such as the bulbous nose of male Proboscis Monkeys, the pendulous resonating chamber of male Elephant Seals, the hydrostatic facial tentacle of proper elephants, and even the chins of Elephantnose Fish. Milewski & Dierenfeld (2013) argue the terminology has become “dysfunctionally vague” and in need of a massive overhaul. The authors trash the term ‘trunk’ as it is vague and redundant (being a synonym for ‘torso’) and lacks precedence over ‘proboscis’, which was originally applied to elephants and roughly translates as ‘forager’. Due to this etymology and the extreme morphology exhibited by elephants, the term ‘proboscis’ was redefined to be a tubular extension of nasal and lip musculature capable of grasping food (Milewski & Dierenfeld 2013). The only extant non-Proboscideans to fit this definition are tapirs, and while numerous extinct mammals have been interpreted with proboscides (Palorchestes, Cadurcodon, Brachycrus, Macrauchenia, Pyrotherium) only Astrapotherium has a good case for having a proboscis under this new definition, since it doesn’t appear to have been capable of feeding itself otherwise.

This Mountain Tapir demonstrates that if narial tubes are wrapping around food, it’s a proboscis. From Wikipedia Commons.

As for other nasal structures that are incapable of grasping food, those have now been termed ‘prorhiscis’. These, uh, ‘prorhiscides’ (?) have disparate functions ranging from a directional sense of smell in Elephant-Shrews, dust filtration in Saiga, thermoregulation and water conservation in Dik-Diks, amplification of roars in Elephant Seals, and possibly acting as a buoy for diving Moose (Milewski & Dierenfeld 2012). There are other weird structures formerly labeled ‘proboscis’ in fish, but that’s really a story for a different time.

The snout of a Saiga rivals that of Tapirs in length, but does not incorporate the lips or grasp food, and is thus a prorhiscis and not proboscis. From Wikipedia Commons.

Gingerich et al. (2005) interpreted the extinct whale Makaracetus as having a “trunk” or “short, muscular proboscis” but confusingly referenced tapirs, manatees and walruses as “imperfect models”. Were they proposing an elephantine proboscis, prehensile lips, or something in between? This is a great example of how the now-archaic terminology was “dysfunctionally vague” and in light of Milewski and Dierenfeld’s efforts, it’s time for a reassessment.

Dorsal and lateral views of: Makaracetus (top) from Gingerich et al. (2005); Artiocetus (bottom) from Gingerich et al. (2001)

Makaracetus is classified as a protocetid and appears fairly similar to species such as Artiocetus (above), although with four pronounced differences: a nasal vestibule extending to the end of the snout, a downward-deflected rostrum with two rather than three pairs of incisors, “extraordinary” fossae (labeled LFM, LFP above) suggesting massive facial muscles, and enlarged antorbital canals (labeled AF above) indicating increased blood supply to the end of the snout (Gingerich et al. 2005). Clearly something odd was growing on the face of Makaracetus, but without living protocetids, it’s a bit hard to tell just what. I’m not even certain if a Tapir-style proboscis can be distinguished from a prorhiscis without live specimens, so, unfortunately, it appears there’s just no way of knowing things for certain. That won’t stop me from rampantly speculating.

Top: Makaracetus
Second: Brazilian Tapir from Witmer et al. (1999)
Third: West Indian Manatee from Husar (1994)
Last: Walrus from Wikipedia Commons

Imperfect models indeed. Gingerich et al. (2005) compared Makaracetus and Tapirs on the basis of expanded nasal vestibules, however, the nasals of Makaracetus are only around half as retracted. Makaracetus and Manatees were compared on the basis of being aquatic and having down-turned rostrums, which Gingerich et al. suggested to be an indicator of benthic feeding. Walruses were suggested as an ecological model, namely as a species that uses facial muscles to prey on bivalves, despite having some very different anatomy. The proposed ecology seems reasonable — although it requires better-known teeth to confirm — but as for what was happening with the nose of Makaracetus, there are some more interesting models.

Makaracetus-Camel

Dromedary from Harvard Museum of Natural History.

Superficially, Makaracetus looks kinda camel-y. The rostra of the two species, while differing considerably in depth, appear to be deflected downward at a similar relative place and to a similar degree. Camels have one less pair of incisors than Makaracetus and, oddly, the placements of the remaining incisor pair, canine, and first premolar are comparable. The antorbital foramen (“AF”) of the camel appears to be larger than that of Makaracetus. There are of course several pronounced differences between the two, namely, the fossae in Makaracetus (LFM, LFP) do not appear to have equivalents in camels and, perhaps as a result of these structures, Makaracetus has a rostrum that looks spoon-like when viewed above and camels don’t. Makaracetus and camels undoubtedly had enlarged noses for very different reasons, but this comparison makes a proboscis or even prorhiscis seem unlikely in the whale.

But I’m not quite done with Makaracetus yet, I haven’t even talked about pigs and moose! That will have to wait for a followup to this increasingly out-of-control article.

References:

Gingerich, P. et al. (2005) Makaracetus bidens, a New Protocetid Archaeocete (Mammalia, Cetacea) from the Early Middle Eocene of Balochistan (Pakistan). Contributions from the Museum of Paleontology 31(9) 197—210. Available

Gingerich, P. et al. (2001) Origin of Whales from Early Artiodactyls: Hands and Feet of Eocene Protocetidae from Pakistan. Science 293 2239—2242. Available

Husar, S. (1978) Trichechus manatus. Mammalian Species 93 1-5. Available

Milewski, A. & Dierenfeld, E. (2013) A structural and functional comparison of the proboscis between tapirs and other extant and extinct vertebrates. Integrative Zoology doi: 10.1111/j.1749-4877.2012.00315.x

Witmer, L. (1999) The proboscis of tapirs (Mammalia: Perissodactyla): a case study in novel narial anatomy. Journal of Zoology 249 249—267. Available