The Mercury picture (below) from De deorum imaginibus libellus / Albrici / Reg. Lat. 1290 (c. 1400) has strange feet (at least), possibly also understood as bird's feet.
That's the third picture, that I found for the theme "Mercury with bird's feet". Would be nice to know more of them.
Bird's feet are quite common for devils, especially Tarot devils. Devils are naturally somehow "bad guys", but one has some problems to assume from Mercury, that e should be a bad guy.
Two of these "Mercury with bird's feet" are from Nuremberg, called Nürnberg in German language. This is a city in the German region "Franken", elsewhere known as "Franconia".
This is the second, also from a Nuremberg context (1502 ... so close to the star map of 1503):
"Franconia" should be the place, where the "Fränkische Losbuch" found to some existence, the oldest of the texts, which led to my occupation with the theme "The Pope and the Donkey
The Fränkische Losbuch (estimated to be from 1425-50) contains a sort of astrology, in which birds - somehow - seem to have been presented "planets". It uses a system of 22x22x22x22 elements.
One of the 22-groups contains 13 zodiac signs (1-13; 12 normal zodiac signs + a bird - a crow), 5 others, which I take as planets (14-18; 4 birds and a camel), 2, which I take as animals for sun + moon (19-20; a dog and stag) and 2, which present Emperor and Pope (accompanied by hare + donkey
The problem "Mercury with bird's feet" observed in Nuremberg 1502/03 remembered myself on the lot book made in Franconia some time earlier.
Nuremberg had been clearly a city wth persons interested in astronomy, at least since the time of Regiomontans, when he founded a publishing house there for astronomical topic 1471-75. Nuremberg might have been a city with astronomical interests before, but my knowledge is limited in this question. I just remember, that Johann the alchemist, father of Barbara of Brandenburg, who married to Mantova around 1437, had ideas in this directions and some relation to Nuremberg.
http://en.wikipedia.org/wiki/John,_Marg ... g-Kulmbach
In my opinion (and my theory to the Fränkische Losbuch) the idea, that birds present "planets" had been very old, possibly going to the Greek time 400 BC.
Further I observed a later love of astronomers to birds.
This star map ...
http://en.wikipedia.org/wiki/Johann_Gab ... c_1730.jpg
... from 1730 and from a man, who was born in Nuremberg, Johann Gabriel Doppelmayr, ...
... shows many birds as star pictures at the Southern heaven.
I was surprized by so much birds, and studied their origin.
Corvus, the crow, is an old star picture.
Tukan is still a star picture, was invented by Johannes Bayer in 1603. A man from Augsburg, so not too far from Nuremberg.
Grus (crane) is still a star picture and was also invented by Johannes Bayer.
Phoinix is still a star picture and Bayer took it from Keyser and Houtman.
Pavo (peacock), close to Indus, is still a star picture and Bayer took it from Keyser and Houtman.
Another source gives this context:
Keyser and Houtman, on the request of an astronomer Petrus Plancius, observed many Southern Stars during an exploration journey 1595-97. All these observations were put together by Johannes Bayer in his Uranometria. "This was the first atlas to cover the entire celestial sphere."
On this 12 new constellations were formed:
"Twelve constellations in the southern hemisphere that were first described by Johann Bayer in his 1603 star atlas Uranometria. They are Apus (the Bird of Paradise), Chamaeleon, Dorado (the Goldfish), Grus (the Crane), Hydrus (the Lesser Water Snake), Indus (the Indian), Musca (the Fly), Pavo (the Peacock), Phoenix (the Firebird), Triangulum Australe the Southern Triangle, Tucana (the Toucan), and Volans (the Flying Fish)."
A lot of flying objects, inclusive Musca, the fly, and Volans, the flying fish. The old collection of star pictures based on the data used by Ptelomy had only 4 flying objects of 48.