Geology history in caricatures: Lyell's time circles

After naturalists realised that species can become extinct, they tried to find an explanation for the apparent succession of animals in the geological record.

In 1717 the French naturalist Buffon proposed an elaborated view of the history of earth and life: phases of stability and prosper are disrupted by single disasters, from which new life is born. This idea of catastrophism developed and survived until the 19th century.

Meanwhile for the geologists the stratigraphic succession was not a linear record, but like the annual revolution of earth around the sun a cyclic event.
John Playfair (1748-1819), Scottish geologist and mathematician, summarizes the ideas of his friend, the geologist Hutton (1726-1797):

"The geological system of Dr. Hutton, resembles, in many respects, that which appears to preside over the heavenly motions. In both, we perceive continual vicissitude and change, but confined within certain limits, and never departing far from a certain mean condition, which is such, that, in the lapse of time, the deviations from it on the one side, must become just equal to the deviations from it on the other. In both, a provision is made for duration of unlimited extent, and the lapse of time has no effect to wear out or destroy a machine, constructed with so much wisdom. Where the movements are all so perfect, their beginning and the end must be alike invisible"
(pag. 431-432 The Works of John Playfair 1822)

For Hutton the unconformities found in the stratigraphic record prove that sediments are deposited in the sea, become mountains, were eroded and the debris is transported back into the sea - an eternal cycle of formation and destruction of which fossils are a part.
It's thanks to the work of Playfair (1802) "Illustrations of the Huttonian Theory of the Earth" - in which he explains in a "simplified" form the idea of Hutton. who was known for his reader-unfriendly style of writing - that the hypothesis of '"uniformitarianism" became widely known and was finally revived, expanded and promoted by Lyell (1797-1875).
Not disasters and rapid changes formed the earth, but slow processes of deposition and erosion, also seen acting in modern times (hence the often synonymous used term "actualism"), needing thousands, if not millions of years (the age of earth was still discussed).
Lyell also adopts the idea of geological time as a cycle. He compares the history of the earth and the climatic changes that have occurred with a "geologic year", with fall, winter, spring and summer - as ordered and similar to the cyclical movements of earth around the sun.
Animal and plant species were perfectly adapted to these "geological seasons". Lyell denied in principle the possibility of extinction, he regarded the apparent patterns in the fossil record as an artefact of the very imperfect preservation of the stratigraphic column, also if a "geological" season ended, some animal and plant species did diminish in abundance (making it more improbable to become fossilized), meanwhile others flourished, a pattern reversible at any time.
According to Lyell so it was possible that

"Then might those genera of animals return, of which the memorials are preserved in the ancient rocks of our continents. The huge iguanodon might reappear in the woods, and the ichthyosaur in the sea, while the pterodactyl might flit again through the umbrageous groves of tree ferns."

That mammals during certain geological periods were not the dominant group was just the fault of the climate, unfavourable for their development, but favourable for reptiles or fish. The discovery of mammalian bones in Mesozoic, known hitherto only in more recent sediments, seemed to confirm Lyell's idea and it was not inconceivable that one could find even more ancient mammals.

This vision of cyclic time inspired one of most famous caricatures in palaeontology. In the same year in which Lyell's "Principles of Geology" was published (1830), in the introduction of a book about natural oddities prominently figured "Professor Ichthyosaurus", lecturing to his fellow reptilian students.

Fig.1. "Awful Changes. Man Found only in a Fossil State - Reappearance of Ichthyosauri." - "A lecture, - 'You will at once perceive,' continued Professor Ichthyosaurus, 'that the skull before us belonged to some of the lower order of animals; the teeth are very insignificant, the power of the jaws trifling, and altogether it seems wonderful how the creature could have procured food." The caricature by De la Beches of Charles Lyell as Prof. Ichthyosaurus on the pages of Francis Trevelyan Buckland (Son of William B.). "Curiosities of Natural History".

The caricature was drawn the geologist Henry de la Beche (1796 -1855), who imagined a palaeontology lesson in a distant future, in which, after a climate change, as inferred by the tropical vegetation in the background, giant marine reptiles discuss the inferiority of strange creatures with weak jaws and small teeth - the mammals, who have lost heir dominant role during the ice age period.

References:

HALLAM, A. (1998): Lyell's views on organic progression, evolution and extinction. In: BLUNDELL, D. J. & SCOTT, A. C. (eds) Lyell: the Past is the Key to the Present. Geological Society, London, Special Publications 143: 133-136.
LYELL, C. (1830-1833): Principles of Geology, Being an Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes Now in Operation. 3 Vols. Murray, London.
PLAYFAIR, J. (1802): Illustrations of the Huttonian Theory of the Earth.