Updated June 6, 2024
“It is in these terms that MM. Quoy and Gaimard describe this species which they only glimpsed:
In the month of October 1819, going from the Sandwich Islands to New South Wales, we saw at 5° 28' north latitude many dolphins performing in troupes around the ship: everyone on board was surprised, like us, to see on their forehead a horn or fin curved backwards, as well as that on the back; the volume of the animal was almost double that of the common porpoise, and the top of its body, up to the dorsal, was spotted with black and white.
We focused on observing these dolphins throughout the time they accompanied us; but although they often came close to touching the prow of our corvette, having their upper bodies out of the water, their heads were so buried there that neither Mr. Arago nor we could distinguish whether their muzzle was short or elongated; their appearance could tell us nothing in this regard because they do not soar above the waters like other species. Based on their very particular conformation, we named them Rhinoceros Dolphins (Delphinus rhinoceros)”
- Complements de Buffon, 1838, pages 620-621
 |
| from Quoy and Gaimard, 1824 |
 |
| the above drawing copied in Der Cetacean Oder Walthiere, 1846 |
The Rhinoceros Dolphin is probably one of the better known paper
whales online, often labelled a “crypid whale” alongside the Alula Whale. So of
course, I had to draw it.
Due to the circumstances of the sighting – namely, the dolphins’ refusal to let the seafarers get a good look at them – I didn’t have a ton of info to go off of. But I had a rough physical description and a location. (Also, I just want to acknowledge that my source quoted above is not the original source of the description. However, looking back at other sources quoted in Buffon leave me fairly confident that they copied the text of most of their French sources verbatim. And also I’m lazy.)
Size
The first thing to note was the dolphin’s size -“the volume of the animal was almost double that of the common porpoise." Now, does "volume" here refer to body mass, or body length? And does "common porpoise" refer to the obvious suspect, Phocoena phocoena, or was the original author one of those people who likes to conflate dolphins with porpoises? That's also hard to say. I've seen several old sources refer to various dolphin species as porpoises.
I personally decided to go with Occam's razor and assume "common porpoise" refers to Phocoena phocoena and made the assumption that "volume" refers to length because I feel the length of a swiftly moving cetacean is easier to gauge than body mass. Doubling a Harbour Porpoise's length gives us a length of 3 meters, and this factored greatly into my personal conclusion that the Rhinoceros Dolphin was a misidentified Risso's Dolphin. Raynal & Sylvestre seem to have come to this same conclusion in their 1991 paper Cetaceans with two dorsal fins.
However, in his 2021 paper, Tom Jefferson decides to interpret "common porpoise" as Tursiops truncatus, the Bottlenose Dolphin.
When I considered that "common porpoise" might be referring to a dolphin, my first thought was actually Delphinus delphis, the Common Dolphin, which I've seen used as a Banana For Scale in writing before. Long before Flipper came on the scene and made Bottlenose Dolphins a household name, Delphinus delphis was the archetypal dolphin in literature and art for a long time.
The logical way to resolve this, in my opinion, would be to read the original source (Quoy and Gaimard) and examine the context in which "porpoise" is used in that document. Does it look like the author is knowledgeable on cetaceans and knows the specific species "common porpoise" is usually applied to, or do they use the term "porpoise" to refer to other dolphin species within the text? Like I said, I haven't been able to find the original text. I'd like to assume this is what Jefferson did to come to his Tursiops conclusion, but he doesn't explain his rationale, so as of right now, I'm still split.
Location
The species was spotted between Hawaii and New South Wales, 5°28'. The exact longitude (East/West position) is not given.
.png) |
| Latitude and approximate position where the species was spotted |
HOWEVER, the original description describes the corvette as traveling between "the Sandwich Islands" and New South Wales. I interpreted "Sandwich Islands" incorrectly as the South Sandwich Islands. Sticking a pin between there and NSW puts you squarely in the South Pacific, and so my original sketch resembles a Long-Finned Pilot Whale, a species found in that area.
 |
| Womp womp |
Turns out what was once the "North Sandwich Islands" are now known by the more flattering name Hawaii. With this in mind, I decided to base my Rhino Dolphin on a False Killer Whale. However, I still retained some Pilot Whale features in the design to keep the species somewhat ambiguous.
Anatomy
I’m far from the first to redraw the Rhinoceros Dolphin, but the reason I did not give mine a long beak like a Bottlenose is because all other extant Odontocetes we currently know of that approach the Rhinoceros Dolphin’s size have a round face without a long beak.
And just to elaborate, I believe the ship-following and pod-forming behavior mentioned in the original description is characteristic of a delphinid, as opposed to a pygmy sperm whale, beaked whale, or baleen whale.
I didn’t really have any theories myself until I was nearly finished the drawing, when I decided to look again and see what delphinids matched my size estimate of 3 meters. An almost perfect match was the Risso's Dolphin. As it just so happens, the species is also native to where the Rhinoceros Dolphin was spotted.
 | ||
| photo from giraffa.co |
Bold, white scars against dark grey skin is a signature of the species, acquired through the bites of other whales and the bite of their favourite prey, squid. Some elderly individuals have so many scars, they almost appear pure white.
As for the two dorsal fins, the most common explanation I see is probably also the most plausible - the pod that the crew observed were on the move and traveling quite close together, giving off the impression of multiple whales with more than one dorsal fin..png) | |||
| A pod of Risso's Dolphins traveling quite close together, Steve Sells, Flickr |
Jefferson additionally posits in his 2021 paper that the Rhinoceros Dolphin could be "possibly a shark or mythical creature".
One of my followers on Twitter made the suggestion to perhaps the Rhinoceros Dolphin was a Blaineville's Beaked Whale, and while I could argue the bow riding and pod-forming behaviors doesn't match beaked whales, I cannot be certain that these elements were not exaggerated in the original description. The location matches up, and the size would match Jefferson's estimate of 5-7 meters.
 |
| Blainville's Beaked Whale |
The aforementioned 1991 paper Cetaceans with two dorsal fins examines the Rhinoceros Dolphin and several other cases of duel-dorsaled cetaceans captured in art, and goes so far as to suggest a new scientific name.
“We would propose the name of Cetodipterus rhinoceros if it would turn out to represent a new genus”
As far as I can tell from my basic understanding of taxonomy, if the Rhinoceros Dolphin actually exists, this would be the name given to it upon collecting a holotype.
I could comment more on the 1991 paper, but in all honesty, its existence kind of confuses me. I have no idea what its authors are trying to prove. But if you are a cetaceans with two dorsal fins enthusiast, I suppose it's a must-read.
.jpg) |
| The Rhinoceros Dolphin making a cameo on The Secret Saturdays, a cartoon following a family of cryptozoologists. |
.png)
