Re: Secret of the stinkbird's stink lies in its gut

From: Stephen E. Jones (
Date: Thu Jan 27 2000 - 17:50:47 EST

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    Here is an old 1989 article about the Hoatzin, the living bird with claws
    like Archaeopteryx. There is something even more strange about the
    Hoatzin. It has a stomach like a cow!

    It seems to me that the Hoatzin sounds like a living near relative of
    Archaeopteryx. The article below says that the Hoatzin's "sternum
    otherwise known as the breastbone where the flight muscles are attached,
    is undersized to make room for its voluminous fermentation apparatus".
    Welnhofer, in a major article on Archaeopteryx says that: "It is pertinent
    that no sternum, or breastbone, can be found in any of the specimens, even
    the large, presumably mature Solnhofen animal. Apparently, Archaeopteryx
    had not developed an ossified (or bony) sternum, a structure important to
    flight in today's birds." (Wellnhofer P., "Archaeopteryx", Scientific
    American, May 1990, p46).

    My Encyclopaedia of the Animal World, says that: "T.H. Huxley believed it
    to be more ancient than the Galliformes, a very old group which includes
    the pheasants, and he may be right. The hoatzin is placed in a family and
    suborder of its own, at present within the Galliformes, although some
    authorities consider it should be quite separate." (Driver P.M., "Hoatzin",
    Encyclopedia of the Animal World, [1977], Bay Books: Sydney, Australia,
    1982, reprint, Vol. 10, p951). This was based on a comparison of its egg
    proteins: " However it is finally classified, the Galliformes are almost
    certainly its closest relatives as shown by a number of features including the
    nature of the egg-white proteins." (Driver P.M., 1982, p951). But now its
    nearest neighbour protein-wise is the Cuckoo!: "Although it was formerly
    placed in the Galliformes--the order that includes quails, grouse, pheasants,
    and peacocks--the hoatzin, based on evidence from studies of egg-white
    proteins, should be assigned to the subfamily Crotophaginae of the family
    Cuculidae (the cuckoos)." (Encyclopaedia Britannica,,5716,11872+as

    Driver explains away the similarities between the Hoatzin and
    Archaeopteryx by invoking "redundance and convergence": "The primitive
    appearance and flight of the hoatzin and the claws on the 'hand' of the
    young compel a comparison with Archaeopteryx, the first known bird.
    However, these similarities have probably come about through redundance
    and convergence in the hoatzin and are not indications of any close
    relationship." (Driver P.M., 1982, p952).

    If Hoatzin was a "living fossil" conserving the claws and digestive system
    of the earliest birds, apart from being another example of stasis, thus
    embarrassing the Darwinists (which probably explains why it is not so
    regarded), it might throw some light on the ancestry of birds?


    New Scientist 30 September 1989 15


    Secret of the stinkbird's stink lies in its gut

    THE EXOTIC hoatzin of Venezuela smells like fresh cow manure,
    according to the first naturalists who arrived downwind of the bird in 1886.
    A century later, zoologists have discovered why: it has a stomach like a

    Common scents dictated the common name for Opisthocomus hoazin, the
    stinkbird. It is one of few birds that eat nothing but leaves. To digest this
    fibrous food and remove the toxic compounds that many leaves contain,
    the bird employs "foregut fermentation", as ruminants and a few other
    mammals do (Science, vol 245, p 1236). The hoatzin is the only bird
    known to ferment food in its foregut, the oesophagus and crop.

    The hoatzin is small weighing about 750 grams. It ranges from Guiana to
    Brazil. A flying animal that eats plants containing little protein, and which
    has to produce its own heat to maintain its body temperature, must
    assimilate energy very efficiently. The bird selects what it eats carefully
    picking the most nutritious species and new growths. But it also makes the
    most of its leafy food with the help of microbes in its gut, which ferment
    the leaves. The arrangement allows the bird to eat a wider range of
    leaves and digest more of each leaf. To improve digestion further the
    hoatzin holds its food in the gut for as long as 43 hours to give the
    microorganisms a chance to work.

    Superdigester: the bird that thinks it's a cow and has a gut to match (right)

    Upper oesophagus

            Lower oesophagus


            Crop Gizzard

                    Small intestine

    The hoatzin seems to pav a price for its novel diet: it is a very poor flier.
    The bird's sternum otherwise known as the breastbone where the flight
    muscles are attached, is undersized to make room for its voluminous
    fermentation apparatus.

    Now a team from the US, Venezuela and Scotland has investigated the
    hoatzin's gut: the researchers believe that the hoatzin's gut: the researchers
    believe that the hoatzin's digestion, and its loss of flying skills, might
    explain some unusual features of its anatomy and behaviour. Young
    hoatzin have functional claws on the first and second digits of their wings,
    rather like those of Archaeopteryx. They use them for the same purpose, to
    haul themselves up trees. They also fling themselves into water when
    threatened by a predator.

    Given that leaves are a huge resource. the researchers are puzzled why
    other birds have not developed a cow-like gut to cope with them.

    "Secret of the stinkbird's stink lies in its gut", New Scientist, 30 September
    1989, p15)


    Stephen E. (Steve) Jones ,--_|\ Email:
    3 Hawker Avenue / Oz \ Web:
    Warwick 6024 -> *_,--\_/ Phone: +61 8 9448 7439
    Perth, Western Australia v "Test everything." (1 Thess. 5:21)

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