Several prominent series of organisms have been used in the past as evidence of evolutionary development: invertebrates, vertebrates, and plants. In response to different kinds of environments, organisms are said to display continuous powers of unlimited adaptation. Thus, linear arrangements of fossil "species" or living species have been imagined to project a hypothetical phylogeny to support gradual evolution (Darwinism).

Ammonite series When Darwin proposed his theory of evolution in 1859, there were no actual examples of evolutionary series. However, in 1869, Waagen used fossil cephalopods to illustrate such a series (Osborn, 1917). Paleozoic rock layers have a diverse group of invertebrate fossils. Within this era are the Devonian strata which contain ammonite cephalopods similar to chambered nautiloids which are still alive today. Evolutionists believed that there was support for a progressive series of shell shapes and complexity of chamber sutures. This change in gross morphology was used in the textbooks of the period, 1917 - 1965 (Osbom, 1917; Lull, 1945; Storer and Usinger, 1965), as visual evidence that these invertebrates evolved until the Cretaceous period. Such changes were said to accumulate in a certain direction and were called Mutationsrichtung by Waagen.	Ammonite series Click thumb-nail image to see larger picture (53K about 21 seconds on a 28.8 modem)
Since no ancient ammonites are presently living, it is not possible to be sure what the sutures represent, as they relate to the annual growth of the invertebrate. It could be an expanded complexity of suturing over time, which is what the evolutionist has inferred. Or it could be simply genetic variation of the suture trait.
Horse series Without doubt the strongest case for seeing evolution in the fossil record has been made for the horses. Starting in the Eocene period of the Cenozoic era, a fossil named Hyracotherium was suggested as the ancestral progenitor of all horses (Lull, 1945, p. 591). A progression of increasing overall size, loss of toes, and change in teeth structure was put forth to argue this point of view. Fortunately, this evolutionary story is being told less frequently except in out of date biology books (Curtis, 1977; Norstog and Meyerriecks, 1983). The biggest objection is that many of the supposed sequential species of horses were contemporaneous in the rock strata. Today, textbooks are decrying the direct line (orthogenic) progression and emphasizing a branched bush mode of evolution (Campbell, 1993). However, the end result is still a linear progression which has all the flaws of the former interpretation.	Horse series Click thumb-nail image to see larger picture (20k about 11 seconds on a 28.8 modem)

Gould wrote about directionality in evolution and horses in particular,

"If a clade has been markedly unsuccessful and now lies at the brink of extinction with but one surviving twig, then our anagenetic biases click in, and we often read the single extant path as an anagenetic trend. Thus, we celebrate little, many-toed Eohippus marching towards the large, noble, single-toed Equus. But Equus is the sole survivor of a tree once lush and vibrant (in an early Tertiary world with few artiodactyls and abundant perissodactyls. We speak of the anagenesis of horses only because our biases abstract bushes as ladders, and the clade of horses has been so depleted that only one lineage remains to be misread as the terminus of a trend. All our textbooks cite horses as the prototypical evolutionary trend, but there is no classical tale about the evolutionary 'trend' of antelopes, rodents, or bats—though these are the true success stories of mammalian evolution by the more appropriate criterion of increasing representation." (Gould, 1988)

Elephant series

Elephant series Evolutionary series have been developed for the elephant using teeth, tusk and proboscis. Click thumb-nail image to see larger picture (18k about 8 seconds on a 28.8 modem)

Plant series Three general lines of evolution have been suggested for green algae (Class Chlorophyceae): a volvocine line, a tetrasporine line, and a siphonous line (Scagel et al., 1965). Each line is considered to have started from a single algal cell type and evolved into more complex growth forms (colonial series, uninucleate series, and multinucleate series, respectively). The forerunner for the three series is thought to be a single, biflagellate mobile cell called Chlamydomonas.

Plant series Click thumb-nail image to see larger picture (62.5k about 25 seconds on a 28.8 modem)

In the volvocine series, Chlamydomonas is thought to have evolved into a larger colony or ball of cells embedded in a gelatinous matrix with an increasing number of flagellated cells. Thus, Chlamydomonas ->, Gonium ->, Pandorina ->, Pleodorina ->, Volvox. However, this series does not appear to have any more complex structure than the rotating ball of Volvox; this series reached a dead end quickly. The larger the colony, the more specialized are the cells into vegetative and reproductive cells.

Keep in mind that this series is an imaginary construct for there is no evidence that Chlamydomonas ever evolved into any other aggregate. Cultures of these species always reproduce faithfully after their kind and do not hybridize naturally.

Reference
1. Campbell, N. A., Biology (1993, Redwood City, CA, The Benjamin/Cummings Publishing Company), p. 483.

2. Curtis, H., Invitation to Biology (1977, New York, NY, Worth Publishers, Inc.), p. 460.

3. Gould, S. J., "Trends as Changes in Variance: A New Slant on Progress and Directionality in Evolution," Journal of Paleontology, vol. 62, May 1988, p. 321. Presidential Address.

4. Lull, R. S., Organic Evolution (1945, New York, NY, The MacMillan Company), pp. 399, 591.

5. Norstog, K. and A. J. Meyerriecks, Biology (1983, Columbus, OH, Charles E. Merrill Publishing Company), p. 170.

6. Osborn, H. F., The Origin and Evolution of Life (1917, New York, NY, Charles Scribner's Sons), p. 138.

7. Scagel, R. F., R. J., Bandoni, G. E. Rouse, W. B. Schofield, J. R. Stein, and T. M. C. Taylor, An Evolutionary Survey of the Plant Kingdom (1965, Belmont, CA, Wadsworth Publishing Company, Inc.), p. 277.

8. Storer, T. I. and R. L. Usinger, General Zoology, (1965, New York, NY, McGraw-Hill Book Company), p. 248.