Gardiner 1982 – a radical hypothesis on reptile relationships

From the Gardiner 1982 abstract:
“The traditional palaeontological view that the mammals separated from the ‘reptiles’ before the origin of all other living amniotes is challenged. A radical alternative hypothesis, based on a character analysis of living tetrapods, is elaborated in which birds are considered the sister-group of mammals, crocodiles the sister-group of those two, chelonians the sister-group of those three, and squamates + Sphenodon the sister-group of those four. The living Amphibia are hypothesized to form a natural group and to be the sister-group of the Amniota. Further, I conclude that the Anapsida, Diapsida and Synapsida are paraphyletic or grade groups and no unique statements can be made about their structure.”

Dr. Brian Gardiner was the professor who exposed the Piltdown man scandal as the work of a student. He teaches vertebrate paleontology at King’s College, University of London and is an expert on fossil fishes and amphibians, and advisor on paleontology to the Natural History Museum in London. He helped write a dinosaur book. While his alternative relationships paper has been cited, it has rarely been supported, even by the Feduccia clade. The Gardiner hypothesis is not supported by the large reptile tree.

The Gardiner 1982 hypothesis was based only on living taxa, thus birds and mammals, both warm-blooded, were grouped together. Originally it was Richard Owen’s idea, as he lumped birds and mammals in the Haemothermia (= Haematothermia).

Gardiner also nested pterosaurs with birds, but not sure how that was pulled off.

Gardiner did make at least two observations that are true based on relationships recovered by the large reptile tree: 1. The traditional palaeontological view that the mammals separated from the ‘reptiles’ before the origin of all other living amniotes is challenged. 2. Anapsida, Diapsida and Synapsida are paraphyletic or grade groups. Earlier we talked about the closure of the diapsid openings in mesosaurs. Earlier we talked about the diphyletic Diapsida. Earlier we talked about the origin of diapsids from basal synapsids, all based on the evidence of the large reptile tree.

I haven’t seen the paper.

Witmer’s View of Gardiner
In Perspectives on Avian Origins Lawrence Witmer writes, “Most of Gardiner’s data came from soft anatomy, although he did consider a few fossil groups.”

Gauthier on Gardiner
Gauthier (1986) praised Gardiner for his cladistic methodology but faulted him for his grasp on the morphology and literature.

Feduccia on Gardiner
In Descent of Birds, Allan Feduccia wrote a short note on Gardiner’s work, reporting it illustrates many of the difficulties inherent in phylogenetic analysis.” As everyone knows, Dr. Feduccia is not a fan of phylogenetic analysis. He’s one of the last stalwarts holding out on the “birds are dinosaurs” work that has been so well supported with phylogenetic analysis.

But wait, there’s more:

From the Gardiner 1993 abstract:
“An exhaustive parsimony analysis of amniote phylogeny using 97 characters has substantiated the hypothesis that mammals and birds are sister groups. This deduction is further supported by parasitological and molecular evidence. The presumed importance of “synapsid” fossils in amniote phylogeny is questioned and it is concluded that they represent a transformation series which, when broken down into constituent monophyletic groups, does not support the separation of the Mammalia from the remainder of the amniotes. Fossil members of the Haematothermia include pterosaurs and “dinosaurs” (both stem-group birds) and Dinocephalia, Dicynodontia, Gorgonopsida and Therocephalia (all stem-group mammals). The Dromaeosauridae are the most crownward stem-group birds and the Morganucodontidae the most crownward stem-group mammals.”

Naish’s view of Gardiner and Løvtrup:
“According to this haematotherm model, birds and mammals are sister-taxa, united by their endothermy, fully divided heart, respiratory turbinates, nerve and vascular characters, and so on. The best known proponent of this concept has been Brian Gardiner; he published a few reasonably lengthy papers on the subject in high-impact journals, the best known of which is Gardiner (1982). Unfortunately, Gardiner has since become best known for this above all else, whereas his writings on vertebrate phylogeny in general, Piltdown, and on Darwin’s correspondence should be better known. 

“Danish embryologist Søren Løvtrup published on the hypothesis a few years earlier (Løvtrup 1977), and later published a paper further supporting the proposal (Løvtrup 1985)*. Both Løvtrup and Gardiner cited and discussed observations made by John Ray in 1693 and Owen in 1866, both of whom supported the idea of a bird-mammal group that did not include other tetrapods (yes, I said 1693 and 1866). Neither Løvtrup nor Gardiner used Owen’s term Haematothermia; instead, they went with the alternative spelling Haemothermia. * I have only recently become aware of the fact that Løvtrup is best known as a staunch critic of evolutionary theory; he has argued that evolution does not proceed as proposed by Darwin, instead occurring via substantial saltational events known as macro-mutations. As was later discussed by a whole string of authors (e.g., Gauthier et al. 1988a, b, Kemp 1988, Benton 1985, 1991), one can only conclude that birds and mammals are especially close relatives within Tetrapoda by ignoring and excluding a vast amount of contradictory data. Løvtrup and Gardiner both ignored fossils, relied predominantly on soft tissue characters, and included only a handful of characters (literally, three or four) that contradicted their favoured topology and supported the traditional one: neither author included or discussed the huge number of bony and soft tissue characters that unite crocodilians and birds, for example. Furthermore, nearly all of the haematotherm ‘synapomorphies’ could be shown to be more widely distributed than proposed, non-homologous, or just plain wrong (e.g., Benton 1985, pp. 103-106).

In summary, Brian Gardiner had his blinders on, refusing to consider all of the evidence. His referees also had their blinders on, for whatever reason, as they approved the manuscript. The good thing is his work was discussed, reviewed and refuted for good reason.

References
Gardiner, B. G. 1982. Tetrapod classification. Zoological Journal of the Linnean Society 74, 207-32.
Gardiner BG 1993.
Haemotothermia: Warm-blooded amniotes. Cladistics 9(4):369-395.
Gauthier, J. A., Kluge, A. G. & Rowe, T. 1988a. Amniote phylogeny and the importance of fossils. Cladistics 4, 105-209.
Naish D 2012. The Haematothermia Hypothesis – Tetrapod Zoology, Scientific American blog 2012/10/03.
Witmer LM 1991. Perspectives on Avian Origins p 427-466. in Shultze H-P and Trueb L eds. Origins of the Higher Groups of Tetrapods: Controversy and Consensus

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