Fossilien

Ein ebenfalls häufig vorgebrachtes Argument ist, daß es keinerlei zweifelsfreie Fossilien von Übergangsformen (sogenannten missing links) gebe. Stattdessen wird die Lückenhaftigkeit der Fossilüberlieferung (fossil record) betont.

Argumentation ergänzen/ausbauen (WuW etc.)

Dazu mehrere Kommentare ( ausbauen, verschriftlichen):

• Die Lückenhaftigkeit der Fossilüberlieferung ist bekannt und wird innerhalb des Evolutionsmodells diskutiert. Grundsätzlich gilt, daß Fossilisierung ein „Unfall“ und nicht der Normalfall für organisches Material ist. Sonst liefen die Kreisläufe des Lebens auch nicht, die darauf optimiert sind, die Nahrungskette an dieser Stelle wieder zu schließen.
• Auch wenn es vielleicht keine zweifelsfreie evolutionäre Übergangsform zwischen zwei höheren Taxa gibt, gibt es doch ausreichend viele Fossilien, die eine aus heutiger taxonomischer Sicht gesehen sehr interessante „Mischung“ von Merkmalen verschiedener Taxa aufweist und die sehr gut zum „Herumspielen“ (tinkering) mit Eigenschaften paßt, wie man das von einem blinden Mutations/Selektionsprozeß erwarten würde, wie Darwin ihn vorschlug.
• Ein grundlegendes „Problem“ an Fossilien ist, daß meist nur die Knochen erhalten sind und man so nur über die Anatomie und damit einen Teil des Phänotyps Aussagen machen kann. Die Evolution läuft aber primär auf einer genetischen Ebene (Genotyp) ab. Das bedeutet u.a., daß man Unterschiede zwischen Fossilien erst wahrnimmt, wenn sie sich eindeutig in der Anatomie widerspiegeln. Dazwischen kann aber durchaus ein schwer rekonstruierbarer gradueller Prozeß von Veränderungen des Genotyps abgelaufen sein, wie ihn die Evolution beschreibt. Das vermeintlich sprunghafte Auftreten neuer oder geänderter Anatomien in der Fossilüberlieferung steht also nicht im Widerspruch zu einer graduellen Evolution.
  Das ist mit Sicherheit kein originäres und auch kein sehr orginelles Argument. → Blick in die Literatur, inwieweit es diskutiert wird und welche Positionen dazu in der Wissenschaft existieren

Nachfolgend Zitate aus Kapitel 4, überschrieben „Limits to knowledge of the fossil record and their influence on studies of evolution“

The primary factor limiting the study of evolution in modern populations os one of time… The complete process of speciation cannot be observed within modern populations, even over the entire span of human history… The origin of major new strutures, body plans and ways of life have few if any counterparts in changes observed in modern populations; these can only be studied through the fossil record. Carroll, RL: Patterns and Processes of Vertebrate Evolution, Cambridge University Press, Cambridge 2007; p. 57

The absence of fossils may reflect the absence not of particular groups of animals or plants but simply of the aprropriate conditions of their preservation. Carroll, RL: Patterns and Processes of Vertebrate Evolution, Cambridge University Press, Cambridge 2007; p. 62

Since all sedimentation is to some degree irregular and episodic, there is an inherent bias toward a punctuational pattern for any mode other than stasis. On the other hand, it is unlikely that alternating periods of deposition and nondeposition would be such as to produce the impression of gradualistic change from a truly punctuated pattern. Carroll, RL: Patterns and Processes of Vertebrate Evolution, Cambridge University Press, Cambridge 2007; p. 64

With an exceptionally long and continuous stratigraphic record, it should be possible to date fossils from several intervals within the length of species duration; yet in practice this is rarely the case, even in the Tertiary. The vagaries of preservation, the irregularities of deposition, and the infrequent availability of beds that can be used for radiometric dating still make it difficult to establish whether the rarity or absence of fossils linking species is a consequence of a punctuated evolutionary pattern or a result of geological factors, even in the mid-Cenozoic. Carroll, RL: Patterns and Processes of Vertebrate Evolution, Cambridge University Press, Cambridge 2007; p. 68

Changes in physiology and behavior are even more diffucult to compare and nearly impossible to measure in a quantitative manner. Nevertheless, changes in behavior may have been the primary factor in such major transitions as the emergence of land vertebrates from the water, and in the origin of the many lineages of secondarily aquatic vertebrates. Increase in metabolic rate was certainly key to the origin of both ornithurine burds and mammals. Carroll, RL: Patterns and Processes of Vertebrate Evolution, Cambridge University Press, Cambridge 2007; p. 77

So far, none of the genes that have been used in taxonomic studies provides direct evidence of the evoution of morphological structures. Although phylogenies based on molecular evidence may accurately reflect the relative time of divergence of vertebrate groups, they cannot be used to establish how or when specific characters by which we recognized members of these groups evolved. Taxonomic groups are recognized by the presence of one or more unique morphological traits by which all known members can be identified… No matter how accurate the phylogenetic resolution, the fossil record remains the primary basis for establishment of the patterns and rates of morphological change. Carroll, RL: Patterns and Processes of Vertebrate Evolution, Cambridge University Press, Cambridge 2007; p. 80

It is clear from the nature of sedimentary processes and larger-scale geological phenomena that the preservation of the remains of organisms is both extremely rare and extremely irregular… The capacity to determine the patterns and rates of evolution is limited by the fact that both the number of fossils that can can be recovered and our ability to date events decline progressively in older strata… Establishing the relative frequency of punctuated versus phyletic change for life as a whole, or even for mammals throughout the Cenozoic is beyond the capacity of our current knowledge of the fossil record, and this, in turn, is but an unknown fraction of the actual history of the species that lived within this time period. Carroll, RL: Patterns and Processes of Vertebrate Evolution, Cambridge University Press, Cambridge 2007; p. 81

Die Konsequenz des Gesagten ist klar:

Particular problems, such as the nature of the transition between major groups, or the response at the species level to changes in the environment, must be studied on the basis of particular examples of specific taxa over limited time intervals…

The remainder of this book deals with specific examples of patterns of evolution studied through the fossil record. These examples were selected because thy are well documented and demonstrate particular features that are important for understanding how evution operates in different vertebrate groups and over different time scales. The also ilustrate some of the difficulties common to the study of fossils. Carroll, RL: Patterns and Processes of Vertebrate Evolution, Cambridge University Press, Cambridge 2007; p. 81