Methods and conclusions in functional analysis: a reply

This paper is a reply to criticism presented by C. R. C. Paul and R. Cowen in immediately preceding articles in Lethaia. Contrary to the assertion by Paul, the present author did not reject the paradigmatic method but (1) criticized it for its limitations and seemingly erroneous results, (2) applied it to the richthofeniacean and lyttoniacean brachiopods by use of the pump as paradigm, and (3) extended it to include anatomic, metabolic, and phylogenetic considerations that go beyond the structural and mechanistic constraints of the original formulation. The rhythmic flow mechanism was rejected primarily on the basis of evidence for a ptycholophous lophophore in the Productidina. and the relative inefficiency of 'valve flapping' in contrast to ciliary action in pumping nutrient-bearing fluid into the shell. A Chinese blast furnace was claimed by Cowen to employ a single oscillating panel as a pump, but instead this panel must act as a valve that admits air in surges while the draft in the furnace maintains unidirectional flow through the system. This is analogous to ciliary feeding in brachiopods, where undirectional flow is maintained by ciliary pumping, and the valve opens to admit water. A richthofeniid with a Composita entrapped beneath the apertural meshwork is introduced as additional evidence against the likelihood of 'valve flapping'.