Creationism and the Platypus
Copyright © 1997 Jim Foley [Last Update: February 18, 1997] Talk.Origins Archive
really," said Picard, not buying it for a second. "And just where, in all
aspects of creation, can your hand be seen?"
Q smiled toothily. "Why Picard ... who do you think came up with the duck-billed platypus?"
This article is a brief introduction to the platypus, and to arguments that some young-earth creationists have made about it.
The platypus, Ornithorhynchus anatinus is one of the most unusual of living creatures. It is a mammal which has fur and suckles its young, but it also lays eggs, has webbed feet, a bill that looks like that of a duck, and a tail resembling that of a beaver. Males have a poisonous spur on their hind legs which can cause excruciating pain to humans and kill dogs. The platypus and three species of echidna (also known as spiny anteaters) are the only living members of a group of animals called monotremes. Platypuses (or platypi) are small animals; the largest ever found was 5 lbs and just over 2 feet (610 mm) in length. Usually they are only about 1.5 feet (460 mm) in length.
In general, the platypus has a fascinating mixture of reptilian and mammalian features. Mammalian traits include fur and mammary glands. Reptilian traits include the laying of eggs, and a common rectal and urinogenital opening, or cloaca (hence 'monotreme', Latin for 'single hole'). There are a number of skeletal features of the pectoral girdle that are found only in therapsids, extinct mammal-like reptiles thought to be ancestral to mammals. This mixture is even found at the cellular level; the chromosomes and sperm of platypuses display both reptilian and mammalian traits. (Griffiths, 1988)
However the platypus is not a "living fossil", since it does not closely resemble the primitive mammals from which it evolved. It has many specialized features which have evolved since the monotreme lineage separated from that of the other mammals.
The Fossil Record
Following is a list of the platypus fossils found to date. Unfortunately it is quite a short list, as the Australian fossil record is not particularly rich.
In 1971, two fossil platypus teeth were discovered in the Tirari Desert in South Australia. They are about 25 million years old, and have been named Obdurodon insignis. The modern platypus has only vestigial teeth which are replaced by horny pads when it is still a juvenile. The fossil teeth are similar enough to these vestigial teeth to allow identification, and they show that ancient platypuses had teeth as adults.
Since then, central Australia has produced a few more isolated teeth, a fragment of a lower jaw, and a part of a pelvis.
In 1984, an opalised jaw fragment with three teeth in place, belonging to either a platypus or a platypus-like monotreme, was discovered at Lightning Ridge in New South Wales. This fossil was 110 million years old, and is named Steropodon galmani (Archer, Flannery, Ritchie, & Molnar, 1985). It was the first known mammal from the Mesozoic (the Age of Dinosaurs) in Australia. It may have been the largest mammal from the Cretaceous period anywhere in the world, although it is less than twice the size of the modern platypus.
A few fossil teeth were discovered in 1984 at the Riversleigh site in Queensland. This was followed in 1985 by a spectacular find: an almost complete skull of a fossil platypus about 15 to 20 million years old. This has been named Obdurodon dicksoni (Archer, Jenkins, Hand, Murray, & Godthelp. 1992; Archer, Hand, & Godthelp, 1994). Its skull is more generalized, and about 25% longer, than that of the modern platypus. Some other fossils, including a partial lower jaw, have since been discovered at Riversleigh.
In 1991 and 1992, Obdurodon-like teeth were discovered in Argentina in strata dated to 61-63 million years old. They have been named Monotrematum sudamericanum (Archer, 1995). South America, like Australia, was once part of the super-continent of Gondwana, and this find shows that platypuses existed in other parts of Gondwana besides Australia.
What do Creationists say?
Scott Huse (1983) starts his discussion of the platypus by saying:
"Evolutionists insist that the duck-billed platypus is an evolutionary link between mammals and birds."
This quote in itself is enough to show how abysmal Huse's knowledge of evolution is. Evolutionists say nothing of the sort. Anyone who reads any evolutionary literature, even at a basic level, will quickly find out that birds are thought to have evolved from dinosaurs in the Jurassic about 150 million years ago, and that mammals are thought to have evolved from a reptile-like group of animals called the therapsids in the Triassic about 220 million years ago. No competent evolutionist has ever claimed that platypuses are a link between birds and mammals.
Huse may believe that the platypus is thought to be a link between mammals and birds because of its "duckbill". In fact, scientists have always known that the bill has nothing in common with that of a duck except for the shape. The bill of a duck is a hard keratin structure, while that of the platypus is a soft flexible organ packed with electrical and touch sensors. While underwater, the bill is used to explore the environment and find food. (Thus Huse also gets it wrong when he says the the platypus "uses echo location like dolphins"; it does not.)
Huse offers three reasons why the platypus should not be considered a transitional form:
"1. Platypus fossils are exactly the same as modern forms."
Since the most important platypus fossils were found after Huse wrote his book in 1983, one can only wonder what fossils he is referring to. It seems unlikely, given the general level of scholarship of his book, that Huse would have known of the few obscure platypus fossils that had been found at the time (1983). If he did, it should have been apparent that his statement was not only wrong, but the exact opposite of the truth: in the only feature in which they could then be compared, fossil and modern platypuses were significantly different, since the fossil forms were toothed.
As for the rest of the body, Huse's statement is totally unsupported. It would be reasonable to guess that fossil and modern forms might have differed elsewhere in the body, and later finds have confirmed this, at least for the head.
"2. The complex structures of the egg and milk glands are always fully developed and offer no solution as to the origin and development of the womb or milk glands."
The platypus shows its transitional nature here, since the reproductive system is more reptilian than mammalian, while the mammary glands are typically mammalian, except for their large size and the fact that the nipples are non-erectile and covered with hair. Although Huse implies otherwise, platypuses do have a uterus, in which two of the three layers of the shells of their eggs are deposited. (Griffiths, 1988)
"3. The more typical mammals are found in much lower [older] strata than the egg-laying platypus." (Huse, 1983)
Presumably, Huse believes that as a 'primitive' mammal, platypuses should be found far back in the fossil record. When Huse wrote, it was true that the known fossil platypuses were not as old as many other more modern mammals, but this was hardly a problem for evolution. The obvious explanation, that older fossil platypuses existed but had not yet been found, turned out to be the correct one. Steropodon, at 110 million years, is far older than any modern types of mammals. (A second edition of Huse's book was published in 1993, but the section on the platypus is virtually unchanged, and does not refer to any of the more recent finds.)
Doolan et al. (1986) make the following statements about the platypus:
"What about the history of the platypus? Where did it come from? Why is it only found in Australia? All fossils found of it are essentially the same as today's living creatures. It certainly shows no signs of evolution. Its only significant change seems to have been to lose some teeth and shrink in size." (Doolan, Mackay, Snelling, & Hallby, 1986)
Not true; there are other differences between the modern platypus and the skull of Obdurodon dicksoni than size. Archer et al.(1992) list over 20 differences between them. Also, it would be more accurate to say "all teeth" than "some teeth", since the modern form has no teeth as an adult.
"Indeed, evolutionary scientists are baffled about the ancestry of the platypus."
This is not a problem for evolution, since it is clear that any bafflement is due mainly to a shortage of evidence. Actually, similarities with other fossil mammals do give at least some hints to the ancestry of monotremes (Archer, Jenkins, Hand, Murray, & Godthelp, 1992; Kielan-Jaworowska, Crompton, & Jenkins, Jr, 1987)
"They openly admit that nothing is known about its history that can explain its geographical distribution."
Since the platypus is found on only a part of one continent, it is not clear what facts about its geographical distribution are in need of explanation. All monotremes and almost all marsupials are found on a continent which has, except for bats and rodents, no native placental mammals. The evolutionary explanation for this is that placental mammals were not able to get established in Australia before it separated from the other continents, and the distinctive Australian fauna developed from the primitive mammals that lived on Australia at that time. This explains very well why Australia contains almost all living monotremes and marsupials, but has almost no native placental mammals.
The creationist explanation for this unusual distribution is that
"If [platypuses] were on the Ark they obviously swam and walked here from Mt. Ararat. This would have taken years, even centuries. The platypuses could have used any land bridges that existed between Asia and Australia as a result of the drastic lowering of sea level during the ice age subsequent to the flood." (Doolan, Mackay, Snelling, & Hallby, 1986)
Not only platypuses, but all the other marsupials and monotremes would be required to make the same journey, without leaving any evidence of it, either fossil or living, in Asia. Platypuses are, to put it mildly, not well adapted for trekking across Asia. At the same time as this remarkable mass migration of marsupials and monotremes took place, we are expected to believe that not a single placental mammal species from the rich fauna of Indonesia chose to cross these hypothetical land bridges, even though many Indonesian mammals are large and highly mobile. Finally geological evidence strongly indicates that there has never been any land bridge between Australia and Indonesia and the fact that the two countries have totally different faunas confirms it. Sea levels did lower during the ice ages, but never enough to connect Asia and Australia.
The other problem with this "explanation" is that it is ad hoc and explains nothing at all: no matter how animals are distributed, creationists can claim that they just happened to migrate to their existing locations. If a mass migration from Ararat had occurred, animals might be expected to be distributed at random; there is certainly no obvious reason to expect closely related animals to tend to be found in close proximity. By contrast, Darwin devoted two chapters of "The Origin of Species" to showing how the distribution of animals was consistent with an evolutionary history.
Continuing on from "They openly admit ... geographical distribution", Doolan et al. say:
"But then, all they had to go on until 1984 were two teeth, a jaw fragment, a hip- bone from the deserts of north-eastern South Australia, and a skull from north- western Queensland, over 1,200 kilometers [750 miles] away. Evolutionists said these fossil platypus fragments weren't useful, since they were merely 15 million years old."
Doolan et al. appear to be a bit confused here. The skull mentioned above must be the Riversleigh skull, which was found in 1985, after the fossil they are about to introduce, and is a much more complete and informative fossil (although not nearly as old).
"In 1984, however, a platypus jaw with three large teeth was found among a collection of opalised bones at Lightning Ridge in northern New South Wales, and pronounced to be at least 110 million years old. Naturally, evolutionist scientists were excited. It seemed that they had now established the platypus's great antiquity. Before that discovery, they believed no land mammal had been found in Australia in sediments dated older than 23 million years."
"But this platypus jaw did not help the evolutionists discover how the platypus had evolved. The new jaw was bigger than that of the present-day platypus and had larger teeth. If anything, it showed that today's platypus has degenerated since the time of its ancestor." (Doolan, Mackay, Snelling, & Hallby, 1986)
The new fossils do give important information about platypus evolution, indicating that it evolved from a larger toothed form. The statement about "larger teeth" is misleading, since the modern platypus has no teeth at all as an adult. That modern platypuses are smaller than their ancestors is no evidence of degeneration, since small creatures can be just as complex as large ones.
In summary, the features of the living platypus, and the evidence available from its scanty fossil record, are both consistent with the idea that it has evolved from primitive mammals which still had many reptilian characteristics.
Thanks to Chris Nedin and Paul Willis for their helpful comments
Archer, M. (1995). Prehistoric platypus fits the bill. Australian Geographic, 38, 86-103. (discovery of fossils of platypus teeth in Argentina)
Archer, M., Flannery, T.F., Ritchie, A., & Molnar, R.E. (1985). First mesozoic mammal from Australia - an early cretaceous monotreme. Nature, 318, 363-6. (announcement of the discovery of Steropodon galmani)
Archer, M., Hand, S.J., & Godthelp, H. (1994). Riversleigh: the story of animals in ancient rainforests of inland Australia. Reed Books.
Archer, M., Jenkins, F.A., Hand, S.J., Murray, P., & Godthelp, H. (1992). Description of the skull and non-vestigial dentition of a miocene platypus (Obdurodon dicksoni n. sp.) from Riversleigh, Australia, and the problem of monotreme origins. In M.L. Augee (Ed.), Platypus and echidnas. (pp. 15-27). Sydney: The Royal Zoological Society of New South Wales.
Doolan, R., Mackay, J., Snelling, A., & Hallby, A. (1986). The platypus: a freak, a fraud, and now a new finding. Creation Ex Nihilo, 8 No. 3, 6-9.
Gould, S.J. (1991). To be a platypus. In Bully for brontosaurus. (pp. 269-80). New York: W.W.Norton.
Griffiths, M. (1988). The platypus. Scientific American, 258(5), 84-91.
Huse, S.M. (1983). The collapse of evolution, Baker Book House Company.
Kielan-Jaworowska, Z., Crompton, A.W., & Jenkins, F.A., Jr. (1987). The origin of egg-laying mammals. Nature, 326, 871-3.