Scientists have four main problems in trying to understand the origin of flying organisms:
(1) Understanding the origin of flying insects, the oldest known form of flying organisms.
(2) Understanding the origin of flying reptiles such as pterosaurs.
(3) Understanding the origin of birds.
(4) Understanding the orgin of flying mammals such as bats.
Scientists have made no great progress in any of these areas. An example of their lack of progress can be seen when we consider the question of origin of flying insects. An example of the current tall tale told about such an origin is the paper here, a paper by Bruce and Patel entitled "Insect wings and body wall evolved from ancient leg segments." In that paper some scientists attempt to convince us that flying insects evolved from crustaceans. The paper tries to suggest that a little leg (or lobe on the leg) on the front of a shrimp-like organism transformed into a big wing on the back of an insect organism. It says, "two ancestral crustacean leg segments were incorporated into the insect body, moving the leg’s epipod dorsally, up onto the back to form insect wings." Really, and while that mystifying migration and radical transfiguration occurred, a shrimp-like crustacean was also turning into a vastly different type of animal, into an insect?
Crustaceans | Insects | |
Body segments | 2 | 3 |
Number of antennae | 2 pairs | 1 pair |
Wings? | Never | Sometimes |
Chewing appendages | Usually 3 pairs | 1 pair |
Location of appendages | Cephalothorax and abdomen | Head and abdomen |
Respiration | Gills | Tracheal system |
See here for this table's source
In Figure 1 of this paper by Bruce and Patel we have a drawing designed to show us some structural similarity between a part of a crustacean leg and an insect leg. The drawings aren't labeled as diagrams, but are labeled as "cartoons," which doesn't exactly inspire our confidence. When we compare these two "cartoons," we find the structural similarity isn't even very strong. So we get no visual reason for thinking one structure evolved from the other. Since the authors have claimed that insect wings evolved from a crustacean leg or part of such a leg, why aren't they showing a diagram comparing the details of an insect wing and some part of a crustacean? It's because nothing on a crustacean looks anything like an insect wing.
Recently the science news sites had another example of paleontologists making dubious boasts claiming some progress in understanding the origin of flying reptiles. One of the stories appeared in the BBC News, which for many, many years has displayed the most child-like credulity in uncritically parroting any evolution story coming from professors, no matter how ridiculous such a story may be. The story is entitled "Scottish fossil revealed to be pterodactyl ancestor." There is a claim that a creature called Scleromochlus was an ancestor of flying pterodactyls.
There are some gigantic problems here:
(1) We see a skeletal "reconstruction" of this Scleromochlus, along with a visualization of it taken from a scientific paper, and neither shows signs of any wings or wing bones.
(2) Pterodactyls were flying animals with very large winspans of about 6 meters. But in the BBC article we see a photo of a fossil of this Scleromochlus, and the fossil easily fits in the palms of someone's hands. So this Scleromochlus was no more than a few inches long, about the size of someone's palm. So claiming tiny Scleromochlus creatures (without even the beginning of a wing) as some explanation for how we got pterodactyls with huge wings is preposterous, rather like claiming that albatrosses arose from acorns.
In the BBC article a professor claims that these tiny Scleromochlus creatures had "wings of skin attached to a single long, skinny finger." Wings of skin? We see nothing in the visuals in the article justifying any such claim. No such wings are shown. One of the visuals shows a tiny whitish something in the shoulder area of these creatures, with such a tiny whitish something being no more about a thirtieth of the length of the creatures. But since the creatures were palm-sized, such a whitish little something could not have been even half as long as a pea. Calling things so tiny "wings of skin" is baloney, since whatever such little bumps were, they could not conceivably have been wings. And referring to "fingers" on these palm-sized creatures as "long" is also baloney, since such "fingers" must have been very tiny, less than half the size of a pea.
The tale that pterosaurs with 6-meter wingspans arose from tiny wingless Scleromochlus creatures is a transformation tale comparable to Cinderella's white horses arising from Cinderella's white mice, but maybe even harder to believe, because at least the white mice and white horses had the same types of limbs. Why should we have much trust in the statements of paleontologists when they make boasts so dubious, and make ancestry claims so unsubstantiated?
A 1992 paper on the origin of flight in bats tells us that "the fossil evidence for bat origins is extremely sparse," and that "all fossils available only complicate matters." A 2005 paper discussing the origin of bats states "The phylogenetic and geographic origins of bats (Chiroptera) remain unknown." After noting that the earliest bats date from the early Eocene era, we read that "skeletons of these early taxa indicate that many of the anatomical specializations characteristic of bats had already been achieved by the early Eocene, including forelimb and manus elongation in conjunction with structural changes in the pectoral skeleton, hind limb reorientation, and the presence of rudimentary echolocating abilities." The paper then tells us that "evolutionary intermediates between bats and their non-flying ancestors are not known from the fossil record." Quite the missing link.
Paleontologists also have no credible theory to tell of the origin of birds. They tell us that birds evolved from reptiles, but not flying reptiles such as pterosaurs, but non-flying reptiles. Paleontologists have no credible theory to tell of how something as hard-to-achieve as flight could have appeared through any gradual Darwinian process.
With the origin of flight, we have a classic case of a requirements threshold, an extremely important concept that paleontologists and evolutionary biologists like to ignore. A requirements threshold is a minimum level of parts and organization of such parts that must be achieved before something is useful. Consider an airplane. There is a certain number of parts that must exist and be arranged in a suitable manner for the airplane to reach the requirements threshold of being able to take off and land without killing people. Meeting only 60% or 70% or 80% of such a requirements threshold results in an aircraft that is useless but harmless (incapable of lifting off), or worse than useless (being something so unsafe it will tend to kill people riding in it). Below is a table with some rough estimates regarding levels of completion in meeting a requirements threshold for a flying animal:
Level of completion |
Effect |
10% of flying requirements threshold |
Useless |
30% of flying requirements threshold |
Useless |
50% of flying requirements threshold |
Useless |
70% of flying requirements threshold |
Worse than useless. An animal trying to fly will tend to fall and kill itself, or have useless wings that will make it easier for predators to bite it. |
90% of flying requirements threshold |
Worse than useless. An animal trying to fly will tend to fall and kill itself, or have useless wings that will make it easier for predators to bite it. |
100% of flying requirements threshold |
Useful. Animal can fly, and escape predators. |
You have a similar situation regarding the construction of a bridge across a river. Building 50% of a bridge that leads halfway across the river does not result in something 50% useful that transports half as many people across rivers. Building 50% of a bridge that leads halfway across the river results in a suicide machine suitable only for leading drivers to their deaths at the bottom of the river. It's the same thing for building 70% or 80% or 90% of a river bridge: that merely gives you suicide machines that will dump drivers at the bottom of rivers. Requirements thresholds constantly appear in both biology and engineering, and when we properly ponder them, very many a gradualist origins tale will dissolve like the morning mist.
Some have tried to suggest a gradual evolution of flight from animals that could jump between trees. But animals such as flying squirrels first appear in the fossil record about 31 million years ago, while paleontologists claim that birds appeared more than 100 million years ago. You could make a table like the one above, listing levels of completion for being able to jump between trees, and it would be something as problematic as the one above. The problem with jumping between trees is that unless it is done very reliably, it will be worse than useless. An animal that can only jump between trees with 90% reliability will quickly kill itself jumping between trees, as it falls from high distances. Also, animals such as flying squirrels don't look anything like birds. Such animals have arms that birds that don't have, and web-like structures between arms and legs, unlike anything in birds. So it is hard to imagine any transition between tree-jumping animals and birds.
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