Hipporex's Slightly-Inaccurate Photographic Guide to Crocodilia

The Confusing Taxonomy of the Dwarf Crocodile: Osteolaemus tetraspis is currently the only species included in the genus Osteolaemus, with two recognized subspecies. However, a study of morphology published in 2007, and studies of DNA in 2009, 2013 and 2015 indicate that three distinctly different populations of Osteolaemus may merit full species recognition. These are O. tetrapis (Central Africa, except the Congo River Basin), O. osborni (Congo River Basin), and a third possibly unnamed species (West Africa).

First possible species: Central African dwarf crocodile (O. tetraspis) at Zoo Leipzig in Germany (photo by @ThylacineAlive )

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Second possible species: Congo dwarf crocodile (O. osborni) (the one on the left) at Zoo Santillana del Mar in Cantabria, Spain (photo by @Maguari)
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Third possible species: West African dwarf crocodile (O. sp.) at San Diego Zoo in San Diego, California, U.S.A. (photo by @ThylacineAlive)
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Fun Fact: If the Congo dwarf crocodile (O. osborni) is recognized as a valid species, it would be both the smallest crocodile and the smallest crocodilian since it does not surpass 1.2 meters (3.9 feet), bumping Paleosuchus palpebrosus of its title.
 
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Gavialis gangeticus
  • Meaning of Scientific Name: To quote @TeaLovingDave, "the name "ghariyal" derives from the Ghara, an earthenware pot and musical instrument local to the northern Indian subcontinent which resembles the distinctive boss at the end of the snout in male gharials. Gavial or Gavialis is merely an incorrect transliteration into English of this name"; and gangeticus refers to the Ganges River of the Indian subcontinent
  • Common Name(s): Gharial, Indian gharial, gavial, and fish-eating crocodile
  • Species Authority: Johann Friedrich Gmelin, 1789
  • Former Distribution: Asia (Bangladesh, Bhutan, India, Myanmar, Nepal, and Pakistan)
  • Current Distribution: Asia (India and Nepal)
  • Length (Males): 3 to 4.9 meters (9.8 to 16 feet)
  • Length (Females): 2.7 to 3.7 meters (8.9 to 12 feet)
  • IUCN Conservation Status: Threatened - Critically Endangered (CR)
  • Fun Fact: The gharial is efficient and well adapted at hunting fish under water, because of its sharp interdigitated teeth and long narrow snout that meets little resistance in the water. They herd fish with their bodies against the shore, and stun fish using their underwater jaw clap. They do not chew their prey, but swallow it whole.
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Gharials at Prague Zoo Praha in Czech Republic (photo by @JigerofLemuria)

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Gharial at the Los Angeles Zoo & Botanical Gardens in L.A., California, U.S.A. (photo by @Anteaterman)
 
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Tomistoma schlegelii
  • Meaning of Scientific Name: "Schlegl's sharp mouth" = tomos (Greek for "cutting" or "sharp") + stoma(Greek for "mouth") + schlegelii (honoring German herpetologist Hermann Schlegel)
  • Common Name(s): False gharial, Malayan gharial, Sunda gharial, Malay gavial, Malay gharial, Malayan fish crocodile, and tomistoma
  • Species Authority: Salomon Müller, 1838
  • Former Distribution: Asia (Indonesia (including Sulawesi, Sumatra, Java, and Borneo), Malaysia, Thailand, Vietnam, and Brunei)
  • Current Distribution: Asia (Indonesia (including Sumatra, Java, and Borneo), Malaysia, and Brunei)
  • Length: Up to 5 meters (16 feet) but usually shorter
  • IUCN Conservation Status: Threatened - Vulnerable (VU)
  • Fun Fact: Until recently, very little was known about the diet or behavior of the false gharial in the wild. Details are slowly being revealed. In the past, the false gharial was thought to have a diet of only fish and very small vertebrates. But more recent evidence and observation indicate that it has a generalist diet despite its narrow snout. In addition to fish and smaller aquatic animals, mature adults prey on larger vertebrates, including monkeys, deer, water birds, and reptiles. There are even unverified reports of this guy/gal (we don't assume here) taking down cows.
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False gharial at the Singapore Zoo in Singapore (photo by @James27
 
Hipporex said:
Meaning of Scientific Name: "Crocodile from the Ganges;" Gavialis is a corruption of the Hindi word ghariyal which means "crocodile," and gangeticus refers to the Ganges River of the Indian subcontinent
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Incorrect - the name "ghariyal" derives from the Ghara, an earthenware pot and musical instrument local to the northern Indian subcontinent which resembles the distinctive boss at the end of the snout in male gharials. Gavial or Gavialis is merely an incorrect transliteration into English of this name.
 
The next and final post will include a picture of every species to wrap things up so you don't have to flip back and forth to compare all the species.
 
Hipporex said:
First possible species: Central African dwarf crocodile (O. tetraspis) at San Diego Zoo in San Diego, California, U.S.A. (photo by @ThylacineAlive)
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This isn't necessarily true O. tetraspis, as I seem to recall the San Diego stock is not yet pinned down to precise status - Leipzig had the true stock last I heard, perhaps seek out a shot from there?

Also, last I heard the three-species model may itself be too simplistic.

Basically, I wasn't joking when I said this species (plus possible splits in American and Saltwater Crocodile which you failed to highlight) was a good reason why crocodile taxonomy was perhaps too complex and unresolved for a thread right now :P
 
*claps hands* alright let's talk about the dwarf crocodiles...

This is an extremely confusing taxonomic and zoological situation and I don't think we're anywhere close to getting a final answer, however, I will do my best to clear up the confusion as much as possible. As most of us know this complex started as one species with two subspecies, the nominate in West Africa and osborni in the Congo River Basin. Research then suggested the latter was actually a completely separate species and that there was a third, undescribed species living in Central Africa. As more research was done, however, it was discovered that the type specimen for Osteolaemus tetraspis was actually from the Central African population, meaning the the "newly discovered' animals were actually the first discovered and the West African population was left without a name. To my knowledge, the majority of the US and probably European populations stem from this West African population but zoos still erroneously label them as "Osteolaemus tetraspis tetraspis" when they're actually the O. sp. nov. St. Augustine has the only non-West African animals in the US as far as I know. This individual is not Central African, however. Last I spoke to the reptile curator there (he's very responsive to emails I found, but this was a couple of years ago), they believed the individual in question is an osborni. Europe is more complicated than the US seems to be, as they have animals of all three originally proposed species. As @TeaLovingDave mentioned, Leipzig Zoo has true Central African, or O. (t.) tetraspis, animals.

The situation gets even more complicated, though, as there are experts out there who now believe there are potentially up to seven dwarf crocodile species! From what I remember discussing with the owner of Crocodiles of the World in the UK in 2016, there's tetraspis, osborni, West African "type 1", West African "type 2", West African "type 3", and I'm not sure on the other two, I'd imagine the orange cave-dwelling crocodiles might well be one of them. What this means for the captive populations I have no idea. CotW's male is/was (I don't know if he's still there) pure, but I've never heard about the results of the DNA testing they planned to do. After that, I know Whipsnade's and Bristol's animals at the time were all West African "type 1" and that's about it. A list of all the pure individuals in at least the UK and maybe Europe was supposed to come my way at some point, but it never did and quite possibly never will. I'd imagine the fact that the taxonomy is still very much unsettled and that there are a lot of animals still untested makes the creation of such a list more or less impossible.

If you want my opinion as someone who's never read a paper on the seven species theory, I think that's way too many. The evidence may prove me wrong, but I think three or four species with perhaps various distinctive subspecies/morphs/ecotypes is much more likely here.

~Thylo
 
Ladies, gentlemen, hermaphrodites, I present to you Crocodilia...

Alligator mississippiensis (American alligator)
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Alligator sinensis (Chinese alligator)
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Caiman crocodilus (Spectacled caiman)
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Caiman latirostris (Broad-snouted caiman)
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Caiman yacare (Yacare caiman)
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Melanosuchus niger (Black caiman)
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Paleosuchus palpebrosus (Cuvier's dwarf caiman)
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Paleosuchus trigonatus (Smooth-fronted caiman)
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Crocodylus acutus (American crocodile)
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Crocodylus intermedius (Orinoco crocodile)
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Crocodylus johnstoni (Johnstone's crocodile)
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Crocodylus mindorensis (Philippine Crocodile)
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Crocodylus moreletii (Morelet's crocodile)
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Crocodylus niloticus (Nile crocodile)
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Crocodylus novaeguineae (New Guinea crocodile)
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Crocodylus palustris (Mugger crocodile)
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Crocodylus porosus (Saltwater crocodile)
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Crocodylus rhombifer (Cuban crocodile)
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Crocodylus siamensis (Siamese crocodile)
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Crocodylus suchus (Desert crocodile)
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Mecistops cataphractus (West African slender-snouted crocodile)
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Mecistops leptorhynchus (Central African slender-snouted crocodile)
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Osteolaemus tetraspis (Dwarf crocodile)
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Gavialis gangeticus (Gharial)
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Tomistoma schlegelii (False gharial)
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A couple things:
  1. It's to late to edit and turn the photo into a dwarf crocodile from Leipzig zoo.
  2. I'd like to thank @TeaLovingDave for letting me do this thread, even though I probably should've waited.
  3. I'd like to thank all the people whose photos I used for excellent photography skills (mainly @ThylacineAlive and @Maguari because I'm pretty sure I used there photos the most)
  4. If I could I'd rename this thread "The Scientifically Inaccurate Zoochat Photographic Guide to Extant Crocodilia."
 
Hipporex said:
It's to late to edit and turn the photo into a dwarf crocodile from Leipzig zoo.
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Fixed both photographic errors in that post.

Hipporex said:
If I could I'd rename this thread "The Scientifically Inaccurate Zoochat Photographic Guide to Extant Crocodilia."
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Be careful what you wish for ;)
 
TeaLovingDave said:
Basically, I wasn't joking when I said this species (plus possible splits in American and Saltwater Crocodile which you failed to highlight) was a good reason why crocodile taxonomy was perhaps too complex and unresolved for a thread right now :p
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And indeed to add onto this, there are photos of multiple subspecies of some of these species in the gallery, yet all are unrepresented on the thread.
 
TeaLovingDave said:
Basically, I wasn't joking when I said this species (plus possible splits in American and Saltwater Crocodile which you failed to highlight) was a good reason why crocodile taxonomy was perhaps too complex and unresolved for a thread right now :p
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jayjds2 said:
And indeed to add onto this, there are photos of multiple subspecies of some of these species in the gallery, yet all are unrepresented on the thread.
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To add to both of these, there's also the long discussed Saltwater Crocodile complex between the Australian, Bornean, and Indian populations as well as the rumored(?) Nepal gharial and Malagasy crocodile splits.

Should any of these come to pass, thankfully their presence in zoological collections are much, much easier to track.

~Thylo
 
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