Journal archives for September 2022

01 September, 2022

Caudal flagging in Thomson's gazelle compared with goitered gazelle

(writing in progress)

Eudorcas thomsoni is common in the Serengeti and elsewhere in East Africa. However, the following are the only photos I have found of adult females stotting:

This confirms that E. thomsoni erects the tail while stotting, even in adulthood.

What this suggests is that Eudorcas differs from other gazelles in having a clear dichotomy in its caudal flagging. While walking and milling around nervously, the caudal flagging consists of a hanging tail, strobed right across the white buttocks from side to side. While stotting, the caudal flagging consists of erecting the tail.

In normal running, there is no caudal flagging in adults (

However, there is caudal flagging in infants/juveniles ( and

To show the differences from E. thomsoni in caudal flagging, here is Gazella subgutturosa: and and and and and and and and

It is clear that Gazella subgutturosa typically, and consistently, flees with the tail erect. This differs from Eudorcas thomsoni, which has similar caudal flagging only a) in infants, and b) in adults while stotting. It also differs from most other spp. of Gazella.
Here are illustrations of three aspects of the camposematic displays of Gazella subgutturosa, relevant to our current discussion.
Firstly, in we see that the erection of the conspicuous dark tail in mild alarm is accompanied, while the animal is walking briskly away from the intruder, by a noticeable twitching. The tail is peculiarly stiff yet peculiarly twitchy, which I suppose informs the potential predator that the individual is fit and highly strung, as it were.
Secondly, in we see that the tail does seem to be twitched compulsively even when it is hanging down, and the animals do not seem to be alarmed. So G. subgutturosa may be similar in this respect to E. nasalis after all.
Thirdly, the following three photos were all taken in Xinjiang, western China. The first two show how conspicuously dark this rather pale species of gazelle manages to be in snowy surroundings; I suspect some kind of antisheen effect resulting from the microstructure of the surface of the hairs. The third photo, taken in the same region, shows how pale this species can look in snow-free surroundings. Because this species looks so pale in summer, its relative darkness in winter is noteworthy and supports the case for camposematism. I do not yet understand how the same pelage can have sheen effects in some circumstances but antisheen effects in other circumstances. Do you have any explanation?
Gazella subgutturosa:

Gazella subgutturosa:

(writing in progress)

Posted on 01 September, 2022 03:29 by milewski milewski | 0 comments | Leave a comment

02 September, 2022

Re-assessing the quality of paintings of giraffes by Pierre Dandelot

Now that I have studied the details of colouration of giraffes, it is worth going back to a book I have been familiar with for most of my life.

I refer to Dorst and Dandelot, 1970 (, illustrated by Pierre Dandelot with his wonderful watercolours.
I can now re-assess, for example, his rendition of Giraffa tippelskirchi (, which he painted more than half a century ago, when there was little photographic evidence available.
My comments on this painting are as follows:
The head (and particularly the eye) is far too big relative to the rest of the animal. However, this can be seen in the context of a kind of ‘caricaturisation’, of which Dandelot was a master. This straying from strict realism works well for illustrations in a field guide-book.
The markings on this giraffe are generally realistic and true to life, i.e. Dandelot succeeded in conveying the crucial features of the appearance of this species.

He erred in details; e.g. he omitted the small spots on the temples of the head.

Again, this is no problem for the purposes of this painting. This is because more detail is not necessarily better, where the artist’s job is to convey the ‘gestalt’ of the species for purposes of quick identification.
Dandelot gets some details impressively right.

For example, he shows the distinct ‘row’ of spots on the cheek, the darkish ‘chin’, the pedal flag, and the fact that the mane has a different hue from both the ground colour and the blotches of the neck. Dandelot proves how observant he was.
Overall, I give Dandelot’s paintings of giraffes, and G. tippelskirchi as an example, a high score. I doubt that any subsequently published field guide has bettered him. His work really has stood the test of time.

Also see and

Posted on 02 September, 2022 01:43 by milewski milewski | 0 comments | Leave a comment

A new idea for how colouration of giraffes achieves camouflage

Here is a possible explanation for how the camouflage colouration of giraffes works.
As readers know, giraffes are doubly remarkable/exceptional.

  • Firstly they are the only non-cervid ungulates that are extensively blotched/spotted, i.e. here we have ruminants with colouration unusually similar to that of blotched/spotted predators such as big cats.
  • Secondly, giraffes are by far the largest land mammals with camouflage colouration.

Camouflage of this kind only really makes sense, at least to the human eye, where

  • there is much vegetation cover, and
  • the animal has a habitual pattern of ‘freezing’ when alarmed.

Because giraffes do not conform to either of these standards, it is hard to accept that giraffes rely on camouflage.

After all, giraffes are generally typical of low, open savannas rather than dense woodlands; indeed they have always been absent from most of the savannas of central Africa, and instead penetrate arid areas such as

The females typically forage in low stands of acacias, where their necks must be held horizonally to browse ( and and

This means that the animals are not usually hidden by trees.

Furthermore, selective browsers with long legs are continually on the move. Therefore, the movement of locomotion usually ‘blows the cover’ of giraffes – in contrast with big cats which typically remain immobile for most of the diel cycle.

And who has ever seen clear behaviour of ‘freezing’ when a giraffe is alarmed?

This is ambivalent because sometimes giraffes do stand still, and perhaps when alarmed they cease to swish their tails against insects. However, any ‘freezing behaviour’ in giraffes is a debatable concept.
What recently dawned on me is an extension of my explanation w.r.t. the striping of zebras:
The camouflage works not so much as seen by the human eye (which is relatively insensitive to motion), but more as seen by the ungulate/carnivore eye (which is extremely sensitive to movement).
Please recall that I have not suggested that zebras use their stripes to avoid detection by predators. Instead, the argument, in the case of zebras, is that they are reconciled to being easily detected by predators.

However, they use their stripes to dazzle the motion-sensitive visual systems of predators by a kind of flicker effect (which frustrates the predators' attempts to detect lameness/illness/vulnerability).

This effect makes it hard to discern individual vulnerability such as sickness, age and pregnancy.

I suggest that the phenomenon of flicker-distraction may also work to some extent in giraffes. However, but my argument in the case of giraffes is different.
What has dawned on me is that leaves and branches of trees are usually moving, even if the breeze is slight. What this means is that any carnivore surveying a wooded scene may see considerable distraction, which is overlooked in human eyes.

Imagine an individual of a giraffe under a tree, partly obscured by the branches, with the foliage and twigs moving a bit in the wind. The figure can be partly in the shade by day, but the idea applies also at night.

The figure may be hard to see, not so much because its outline is disrupted (which is the classic textbook explanation), but because the eye of the predator is somewhat distracted by the flicker-effect in the whole scene.

What this means is that giraffes are indeed camouflaged in a strict sense (unlike zebras, to which the word ‘camouflage’ does not really apply). However, the camouflage works far better in the eyes of Carnivora than in the eyes of humans.

To us, the camouflage is not really convincing. However, this is because we ‘see through it' with our failure to be flicker-dazzled by either the blotch-lines or the foliage movements. 
Giraffa tippelskirchi thornicrofti, Luangwa, Zambia:

Posted on 02 September, 2022 03:02 by milewski milewski | 2 comments | Leave a comment

Mustelids and procyonids generally seem to have horizontal pupils

(writing in progress)
We have seen that Sarcophilus has a vertical slit/slot pupil much like that of a cat, while Gulo – despite having impressive similarities to Sarcophilus – has a categorically different pupil which forms a horizontal slit/slot.

Important in this comparison is that both Sarcophilus and Gulo have small eyes for the sizes of their bodies.
We have also seen that certain diurnal mongooses, which possess large eyes relative to body size, have horizontal slit pupils.
This leads us to the question of which other carnivores, besides Gulo, have horizontal slit pupils despite having small eyes.
The answer seems to be ‘many’.
The ferret has horizontal slit pupils in small eyes, and it belongs to the same family as Gulo: Mustelidae. It is said that weasels are similar in this way. I have yet to find clear photos in the case of the honey badger or otters, but I suspect that all mustelids have horizontal pupils, the main difference among genera being how long the slot is.
Coatis also have horizontal slit pupils, and they belong to the raccoon family, Procyonidae. Another procyonid, the olingo, also has horizontal slit/slot pupils although these are short. I’d like to know the pupil shape in the case of the raccoon but so far no photos have shown this to me.
Although coatis are diurnal, they are like mustelids in having small eyes relative to body size.
So I have more research to do, but the pattern emerging is that many if not all mustelids and many procyonids do indeed have horizontal slit/slot pupils, in contrast to viverrids and felids as well as foxes (e.g. Vulpes, which certainly has a vertical slit pupil).

And I am getting the impression that, in Carnivora, a major correlate with long, horizontal slit/slot pupils is small eyes relative to body size – certain extremely specialised mongooses being the exceptions because they have big eyes.
Altogether, an intriguing topic well beyond the scope of any comparison between Sarcophilus and Gulo; and in a way Sarcophilus is the least interesting part of this topic, not so?
Mustela putorius:
Procyonidae: Nasua nasua:
Procyonidae: Bassaricyon gabbii:
Compare the above mustelids and procyonids with the following viverrid:
Viverridae: Arctogalidia trivirgata:

(writing in progress)

Posted on 02 September, 2022 05:43 by milewski milewski | 0 comments | Leave a comment

Spectacular counterpart of hyenas in South America

 The role of bone-crunching scavenger is taken

  • in Africa and Asia by hyenas, and
  • in Australia (in a minor way because its body mass is only about 6.5 kg) by Sarcophilus.

I assume that, in the Pleistocene, Sarcophilus extended to New Guinea. And for now I will exclude any gaps presented by southeast Asia.

I have already covered Madagascar (
This raises the question: why do we not hear of any bone-crunching scavengers in South America?
Here, I suggest that not only was there a bone-crunching scavenger in South America, but it was exceptionally large.
As a preamble, let me point out that assessment of the fauna of South America is complicated by two factors. These are

  • the megafaunal extinctions at the start of the Holocene, and
  • the unrivalled proliferation of rodents in the Neotropics.

Rodents, although gnawing bones only incidentally, are numerous, diverse, and in some cases large-bodied, in South America. So much so that it is easy to imagine them consuming any large bones available, without even being noticed doing this.
While I still think the current absence of any obvious bone-crunching scavengers (apart from, perhaps, peccaries) in South America is puzzling, let us put this puzzle aside, and ask ourselves: which animals filled this niche just before the megafaunal extinctions?
The obvious candidates are the genus Arctotherium of the tremarctine bears.
One way to think of Arcotherium is as a ‘superhyena’, with body mass an order of magnitude more than that of any living hyena, and extremely long legs suited to great mobility.
His may lead to the realisation that, at least until the end of the Pleistocene, South America not only had a bone-crunching scavenger, but had the ‘ultimate’ bone-crunching scavenger.

For, just as the sabretooth felid of the Pampas, Smilodon imperator, was the largest cat ever to live on Earth, so Arctotherium was probably the largest bear ever to live on Earth.

And it seems reasonable to assume that the latter scavenged the bones left by the former – a wonderful thing to ponder when we consider the extreme differences and the extreme specialisations in the jaws and dentitions of the two genera.

While Smilodon was ‘the ultimate sabretooth’ with teeth extremely specialised for slicing, but at the same time extremely vulnerable to fracture, Arctotherium complemented this by evolving a dentition that could hardly be more durable in processing large, hard objects by blunt, brute force.
By comparison with this bear, all other known bone-crunching scavengers show a kind of compensation for their limited size.

Crocuta has a skull of modest size, even relative to its body, but relies on an extremely ‘dexterous’ use of its teeth, breaking large bones not with its molars but with one conical premolar on each side.

Sarcophilus relies on uncomplicated force (which is inadequate for breaking bones even as large as the largest bones of kangaroos) and compensates for the inevitable fracturing of its unspecialised teeth by having a naturally short lifespan of about 6 years – which means that it runs out of life and becomes senescent before it runs out of teeth.
Although the existence of Arctotherium is well-known (and as you can see from the artwork below prominent in the imaginations of those who study such matters), there are two points, emerging from this, which I think have been underplayed.
Firstly, Arctotherium is usually portrayed as a predator first and a scavenger second.

I see no particular reason to frame it this way. It seems as logical, and more biogeographically meaningful, to assume that it was a scavenger first, and a predator second.

And, if so, the way we should think of Arctotherium is as ‘the ultimate megafaunal scavenger’ among the mammals.
Arctotherium angustidens:

Posted on 02 September, 2022 07:01 by milewski milewski | 0 comments | Leave a comment

Comparing cat and fisher to show difference in eye size w.r.t. pectoral insignia in mustelids

I have suggested that a common theme among Carnivora with white insignia on the chest of an otherwise all-dark body is poor vision, and an unusual reliance on olfaction.
I would like to illustrate this by comparing the domestic cat (Felis catus) with the fisher (Martes pennanti, and
I have chosen the fisher, among all the Mustelidae, for two reasons:

  • it has about the same body mass as the domestic cat, and
  • it is among the mustelids that have whitish insignia on the chest, the white patches being extremely variable individually, and always asymmetrical.

When one looks at photos of the fisher, the first impression is that there are no insignia on the chest, because by far the majority of individuals are plain dark.

However, as the photos below show, some individuals do indeed have whitish insignia on the chest.
Both Felis catus and Martes pennanti have adult body mass of about 4 kg, the difference being that the mustelid is far more sexually dimorphic in body size than is the cat.

The similarity in body mass is important in any comparison of eye sizes. This is because eye size is hypoallometric: other things being equal, species differ predictably in the relative size of their eyes, with the eyeballs becoming smaller and smaller as the body gets bigger and bigger.
My interpretation of the photos presented here:
Although domestic cat and fisher are like-size, they differ greatly in eye size.

This helps to explain why it is that in small, wild felids there is no such thing as pectoral insignia, whereas in the fisher this pattern is well-exemplified.

It is, of course, true that some individuals of small felids in the selectively bred form of the domestic cat do show colouration that is nearly all-black, with an asymmetrical, irregular white patch on the chest.

However, the important things to realise are that

  • such a pattern is completely unknown in any wild felid of any body size,
  • the appearance of white on the chest is usually accompanied by other irregularities such as an odd white toe, in the case of black individuals of the domestic cat (which occur in 22 breeds, but can hardly be bred into a consistently all-black breed), and
  • seems to be mainly ontogenetic, with all-blackness restricted to adults.

So, what I see here is a situation in which felids, which are typically large-eyed, have virtually no incidence of pectoral insignia, whereas mustelids, which are typically small-eyed, have many such incidences, including that seen in a species most similar to the domestic cat in body size.

The pattern seems to make sense, because

  • relatively poor vision means that bold insignia on the front of the animal are helpful for individual recognition, and
  • such insignia in felids would compromise the crypsis/camouflage necessary for their particular reliance on stalking of prey, something not true for mustelids. 

The following ($_86.JPG) illustrates three features of interest.

Firstly, the large size of the eye relative to body size is typical for felids; indeed this expression of the eyes is a major reason why the domestic cat is so popular.

Secondly, extremely few individuals of the domestic cat actually show this colouration, which is extreme for the species and has no function whatsoever in any wild felid, including the species ancestral to the domestic cat. Note that at least one toe is also white.
The following ( is typical of the relative size of the eye in the domestic cat, a species which weighs – like the fisher below – approximately 4 kg.
Now let us look at the fisher:
The following ( is either a bit smaller or a bit larger than the typical domestic cat, depending on whether it is male or female. I do not know its sex. However, one can see, at a glance, how much smaller the eye is relative to body size than in the cat.

This individual, like most individuals of the fisher, lacks any whitish insignia on the chest. No individual of the fisher has odd white toes; that pattern simply does not exist in this species.
The following ( once again shows the small size of the eyes relative to body size.
The following ( is an individual with irregular whitish insignia, clearly asymmetrical, on the chest and extending in this case also to the front-of-neck, and even the inner foreleg.

Again, nobody could confuse this animal with a cat, even if only because its eyes are so small.

The fisher resembles the wolverine in its insignia, although a smaller percentage of individuals show these insignia in Martes pennanti than in Gulo gulo (

The following ( shows the small size of the eyes well, and also the individually variable whitish insignia on the chest and front-of-neck. A good way to think of the fisher is as a smaller version of the wolverine, somewhat specialised on a diet of Erethizon dorsatum (
The following individual ( again exemplifies the insignia, and again clearly shows how small the eyes are.

Not even the largest felids, such as the lion (Panthera leo), have such small eyes relative to body size. In other words, if this was a felid, it would need to be not 4 kg but 400 kg to show this kind of relative size in its eye.
Once again, if you half-close your eyes and imagine that you are looking at a domestic cat and not the fisher, can you see how this could never fool you as a cat, if only because you would instantly notice that its eyes are far too small?

This individual (, like most, seems to lack any whitish markings. 

The following ( individual again possesses white markings, although in this case they are confined to the chest.

The following ( further illustrates the extreme irregularity of the whitish insignia in the fisher.

Posted on 02 September, 2022 09:45 by milewski milewski | 4 comments | Leave a comment

Striping on neck suggests that extinct quagga is different species from Burchell's zebra

 (writing in progress) 

I come back to the question of the taxonomy of the plains zebra and the status of the extinct quagga: merely the nominate subspecies or a separate species in its own right?
In previous photo-emails I’ve pointed out that the mane of the extinct quagga is different from those of Equus quagga burchellii and E. q. chapmani, and that this incongruency supports the notion that the extinct quagga was distinct.
Perhaps I’ve not gone through the literature thoroughly enough, buy I don’t recall an examination of the neck striping along the lines which I present below.
My focus here is on the question: to what extent does shadow striping occur in burchellii, and is it the case that the neck striping of the extinct quagga is product of extreme encroachment of shadow striping in an anterior direction?
In fact, the neck striping of the extinct quagga does not seem to be the result of ‘exaggerated shadow striping’. Instead, the neck striping of the extinct quagga shows ‘reverse shadow striping’ in which the dark stripes develop relative pale centres. Has this ever been noticed before?
The gist of what I find here is that it is not the case that the neck striping of the extinct quagga is merely an ‘extension’ or ‘extrapolation’ of the trend seen as one moves southwards within the plains zebra. Instead, the neck striping of the extinct quagga, in keeping with the distinctiveness of its mane, is differently configured.
The following shows a specimen of ‘re-bred’ burchellii, in which there is clear encroachment of shadow striping on to the neck. This encroachment tends to occur mainly near the base of the mane, but there is one instance of it also on the part of the neck near the shoulder. If the extinct quagga were merely the nominate subspecies, then we would expect its neck striping to be even more extensively shadow-striped, to the extent of tending to occlude the pale stripes, not so?
The following specimen of ‘re-bred’ burchellii is ambivalent, because it shows both the encroachment of shadow striping on to the neck and the appearance of ‘pale centres’ in the dark stripes on the neck. Note that all specimens of ‘re-bred’ burchelli retain the long, mainly pale mane of the southern forms of plains zebra, including a prominent forelock.
The following specimen of burchellii, presumably in Zululand, again shows shadow striping on the neck.
The following specimen of extinct quagga is fairly typical: the neck striping is not configured by means of exaggeration of the shadow striping shown above in burchellii. Instead, the dark stripes are exceptionally broad and have indications of development of ‘pale centres’, which can be thought of as a kind of ‘reverse shadow striping’. This represents a qualitative rather than quantitative difference from burchellii, in keeping with the differences in the mane, which is shorter and darker in the extinct quagga than in burchellii.
The following specimen of the extinct quagga is ambivalent, showing what could be interpreted as shadow stripin as well as the ‘hollow centres’ to broad dark stripes. The relatively short mane is typical of the extinct quagga.
The following shows the difference I’m describing.
I would have preferred the following to consist of photos rather than these rather poor paintings, but there is some value in it because it summarises the individual variation in neck striping in the extinct quagga. Please note the specimen in Mainz Mal., which seems to hint at an exaggeration of shadow striping.
The following specimen of the extinct quagga shows the typical relative shortness of the mane, the lack of shadow striping on the neck, and the appearance of ‘hollow centres’ in the broad dark stripes on the neck, which I refer to as a kind of ‘reverse shadow striping’ rare in burchellii.
The following specimen of the extinct quagga again shows ‘hollow centres’ rather than exaggerated shadow striping’.

In the following specimen of the extinct quagga, there is once again no indication that the striping of the neck has been formed by means of exaggeration of shadow striping.
In the following specimen of the extinct quagga, there is once again a hint of ‘reverse shadow striping’, not exaggeration of shadow striping.
The following specimen of the extinct quagga has exceptionally broad dark stripes on the neck. However, there is once again no indication that these dark stripes have been formed by means of coalescence of shadow stripes with main stripes. Instead, the only ‘shadows’ are ‘hollow centres’ to dark stripes, not so?
The following specimen of the extinct quagga shows similar patterns to those pointed out above.
The following specimen of the extinct quagga shows the shortness and darkness of the mane particularly well.
The following specimen of the extinct quagga shows an ambivalent pattern in the striping of the neck, but it is noteworthy that this ambivalence does not affect the mane, which is typical in its relative shortness and darkness.

(writing in progress)

Posted on 02 September, 2022 18:30 by milewski milewski | 15 comments | Leave a comment

03 September, 2022

Who has spotted an intraradial signature in the domestic donkey?

@tonyrebelo @capracornelius @beartracker @matthewinabinett @biohexx1 @lonnyholmes @chewitt1 @oviscanadensis_connerties @paradoxornithidae @jeremygilmore @ludwig_muller @grinnin @jacqueline_llerena

Dear reader, before reading this Post, please examine the adaptive colouration in

This specimen of the donkey (Equus asinus) exemplifies a wild-type, symmetrical colouration, free of the erratic markings that selective breeding usually produces in domestic mammals. And this, in turn, implies retention of the original colouration of a wild ancestor.

Which marking or pattern do you find most intriguing?

Now please examine this specimen (

A part of the body to focus on is the inner foreleg, where the chestnut ( is located.

The point to note is that this surface has no striping on the pelage.

The surface in question, around the chestnut, has previously had no anatomical name. However, I will call it the intraradial surface, based on the fact that the leg bone here is the radius (

Now, focus on this specimen:

There is an intriguingly crisp border to the white pelage on the intraradial surface. Furthermore, the outer surface of the foreleg, at the same height, has faint horizontal striping.

In the following mother and infant ( and, the border in question actually takes the form of a distinct - albeit short - dark stripe, running at an angle of about 45 degrees.

Recapitulating for a moment, here is another specimen lacking any intraradial stripe:

Furthermore, there is likewise no intraradial stripe in Equus somaliensis, a fully wild relative of the donkey that retains some striping on the legs in all individuals:

The following shows that there may originally have been a link between the stripe on the inner foreleg and that on the outer foreleg:

In the following (, the whitish has transgressed its usual border, without obliterating the diagonal stripe.

The following are further illustrations:
Here is a description of the intraradial signature:

  • The whitish of the brisket area extends ventrally on the inner surface of the upper fore leg, to surround the chestnut, which is bare skin.
  • The chestnut in the donkey is moderate in size relative to other members of the genus Equus, but usually dark enough to be visible.
  • The border between the whitish pelage and the greyish ground-colour of the rest of the upper fore leg is, in some individuals, emphasised by dark pigmentation.
  • There is often a faint dark stripe on the outer surface of the same fore leg, at about the same height above ground.
  • There is also a somewhat dark vertical streak extending ventrally from the chestnut towards the carpal joint (I do not know if this results from pigmentation of the pelage or some sort of discolouration discharged by the chestnut).
  • This dark/pale/medium tone configuration of small-scale features constitutes a kind of individually variable signature.
  • The intraradial signature is absent - except for the chestnut - from some individuals, even within the 'wild-type' colouration.

Both the ancestry and the adaptive function of the intraradial signature remain to be explained.

So, dear reader, now that you are familiar with this intraradial signature, can you figure out who is who in this view?

Posted on 03 September, 2022 02:09 by milewski milewski | 6 comments | Leave a comment

Even Pierre Dandelot falsely assumed that Somali wild ass is a wild form of donkey

 (writing in progress)
Many naturalists may suppose that the Somali wild ass (Equus somaliensis, is either

However, ‘ancestral donkey’ may be a misconception, for Equus somaliensis.
This is because

Pierre Dandelot, had a fine eye ( and

However, even he was misled by the presupposition that the Somali wild ass is essentially on a par with the Nubian wild ass (Equus africanus) and its extinct relatives, in being an original, wild version of the donkey.
In his watercolour of E. somaliensis (, Dandelot has made three significant errors.
Firstly, he showed the head to be proportionately far too large. In fact, the size of the head in E. somaliensis is unlike that of the donkey, and similar to that of zebras such as Equus hartmannae ( and
Secondly, he showed the ears to be too long – another subconscious aspect of confusion with the image of the donkey.
Thirdly, he underrepresented the length of the mane. Although he correctly captured the dark/pale contrast on the mane, he under-represented the pale proximal band in the mane, as one can see by comparison with the photos below.

Again, he subconsciously painted a mane somewhat intermediate between that of E. somaliensis and that of the donkey.
As a minor fault, Dandelot also failed to portray the colour as steel-grey enough on the body, and cinnamon-hued enough on the head. He erred on the side of fawn, possibly again misled by his conception of important breeds of donkey.
I became familiar with Dandelot’s portrayal of this taxon decades before I became familiar with real photos of E. somaliensis.

Because the earlier programming of my mind took precedence, it took me further decades to bring my feeling of ‘what is wrong with this picture’, while admiring photos of E. somaliensis in zoos, to full consciousness.
Only later in my life have I healed this mental gap.

Now, I see the error:
Everyone initially assumed that E. somaliensis is an ancestral donkey, whereas a better way to think of it is as a zebra with striping restricted to the lower legs.

Once I reconceived E. somaliensis in this way, what happened was that it has not been the real appearance of E. somaliensis that has been the problem, but my false expectations of how it ‘should’ look. And I dare say that thousands of others have a subconscious feeling, every day when beholding photos of somaliensis on the Web, along the lines of “how come I find this animal so splendid, when I know that it is hardly more than a wild donkey?”
Has this not been a case of false assumption and cognitive dissonance?

Has this led to some under-aiming in the collective resolve of conservationists to keep this most handsome of equids from extinction?

(writing in progress)

Posted on 03 September, 2022 06:22 by milewski milewski | 2 comments | Leave a comment

04 September, 2022

Brain size in palm cockatoo

Although the palm cockatoo (Probosciger aterrimus) is only a bit more than one kilogram in body mass, it has a brain of 20.5 ml volume, equivalent to approx. 20.5 grams mass. This is an astonishingly large brain considering that the domestic cat, which weighs more than three-fold more, has a brain mass of approx. 30 g. The short-beaked echidna and bat-eared fox both weigh about 4 kg, and their brain masses are respectively 25 g and 28.5 g. So, if one compares palm cockatoo with echidna, the body masses are about four-fold different but the brain masses are not much different: about 20 g in the bird and about 25 g in the monotreme.

Subject: from antoni: most recent paper by iwaniuk et al. on braininess in australian birds

Subject: from antoni: valuable information on encephalisation quotients in many mammals
This is my commentary on the data shown below, for encephalisation in various mammals.
The following species fall below the threshold EQ of 0.5. All these species have brains less than half as massive/voluminous as predicted for the average mammal of their body mass:
armadillo Dasypus novemcinctus 0.44: this species is as decephalised as bandicoots, but I think this is largely for a different reason, i.e. the heavy armour of armadillos
hedgehog Erinaceus frontalis 0.36: conforms to the generalisation that armoured mammals are decephalised
Hippopotamus amphibius 0.37: the decephalisation of the larger of the two extant spp. of hippos is noteworthy, but difficult to make sense of, partly because all mammals > 1 tonne in body mass tend to show a kind of breakdown in the allometric relationship applying to smaller mammals
guinea pig Cavia porcellus 0.4: all caviomorph rodents tend to be brainy compared with non-caviomorph rodents other than tree squirrels, but even the caviomorph rodents show a general pattern in which rodents and lagomorphs are small-brained relative to e.g. primates of similar body mass; I also suspect that the domestic guinea pig is decephalised relative to its wild ancestor
beaver Castor canadensis 0.4: my interpretation here is similar to that above for cavies
Sus scrofa (domestic) 0.44: pigs (Suidae) are oddly decephalised, not only by domestication but even in the wild ancestral species
The following species fall only slightly above the threshold of 0.5:
anteater Tamandua 0.52: South American anteaters are decephalised, which is unsurprising for termite- and ant-eaters with slow metabolism; however, the ant-eaters are not as decephalised as the armadillos
eland 0.56: I suspect that decephalisation in large ruminants is rather misleading, reflecting the fact that males continue to grow brawn to full maturity while their brains remain at the size of the adult female
domestic rabbit 0.51: my interpretation here is similar to that for rodents and cavies, above; it is interesting that the feral rabbit in Australia is almost as decephalised as the native bandicoots while reproducing far more rapidly than the bandicoots
Rats and mice about 0.5: these rodents are more intelligent than their values for EQ might indicate; I don’t know why rodents differ from primates in having a different ratio of intelligence to encephalisation, but that seems to be the case
Sus scrofa (wild) 0.54: see my remarks for the domestic descendents of this wild species; it is odd that the wild boar is so decephalised relative to other cloven-hoofed mammals
Other noteworthy species:
Note that the porcupines Hystrix cristata has similar EQ to the capybara, the values being respectively 0.63 and 0.67. Porcupines seem not to conform to the rule that armoured mammals are decephalised; this porcupine actually beats the guinea pig in EQ
tree sloths 0.63-0.71: rather surprisingly, sloths are not as decephalised as other Xenarthra despite having extremely slow metabolism
bat-eared fox Otocyon megalotis 1.16: although this insect-eating species is decephalised relative to typical foxes in the genus Vulpes, it remains brainy relative to the average mammal of its body size; this is testimony to the fact that Canidae are one of the brainiest families of Carnivora

Posted on 04 September, 2022 09:17 by milewski milewski | 0 comments | Leave a comment