Garstang's vision, of the adaptations of ancestral larvae providing body-plans for
descendants, was a useful model for the origins of new phyla. However, the concept of …

Evolution has been integrated with embryology during two great periods: the latter half of the
19th C as evolutionary morphology/embryology, and the latter third of the 20th C as …

What is a larva, if it is not what survives of an ancestor's adult, compressed into a transient
pre‐reproductive phase, as suggested by Haeckel's largely disreputed model of evolution by …

It is postulated that some groups of animals have hybrid life-histories, with the larva
originating in a different evolutionary line from that which produced the adult. Later the two …

The origins of bilaterian animal body plans are generally thought about in terms of adult
forms. However, most animals have larvae with body plans, ontogenies, and ecologies …

Bilaterian animal body plan origins are not solely about adult forms. Most animals have
larvae with body plans, ontogenies and ecologies distinct from adults. There are two primary …

Hypotheses that provide explanations of major transitions in early vertebrate evolution can
be tested by analysis of fossils. In this chapter I consider two widely held views of early …

Many biological facts are irreconcilable with the assumption that larvae and adults evolved
from the same genetic stock. The author of this book draws attention to these, and presents …

(i) Varied origins of larval forms and metamorphoses are indicated by comparisons among
extant animals.(ii) Size-specific and stage-specific constraints on survival and growth may …

Contrary to general belief, there has not been a reliable, global phylogeny of animals at
hand within the past few decades. Recent progress in molecular phylogeny is rapidly …