Evolution Icon Evolution
Paleontology Icon Paleontology

Fossil Friday: Scansoriopterygidae, Bizarre Bird-Like Dinosaurs, Illustrate Darwinist Trickery

December 15, 2023, 6:35 AM
Photo credit: i qi, Xu et al. 2015 fig. 1a, fair use.

This Fossil Friday is dedicated to Scansoriopterygidae, which “truly are one of the most bizarre clades of non-avian theropods” (Wang et al. 2019). These fossil animals are known only from the Middle to Late Jurassic of China with the genera Ambopteryx, Epidexipteryx, Scansoriopteryx (= Epidendrosaurus?) and the featured Yi. Scansoriopterygidae were very small (sparrow to crow sized) feathered dinosaurs, characterized by an enlarged third finger and ribbon-like tail feathers (Zhang et al. 2008).

Their phylogenetic position among dinosaurs and early birds is unclear (Turner et al. 2012, Cau 2018) and highly disputed, so that no consensus has emerged in spite of several well-preserved fossils. Czerkas & Yuan (2002) placed scanoriopterygids as close relatives to Archaeopteryx and birds, but outside of theropod dinosaurs, while most other studies consider them as theropod dinosaurs. Some studies placed them in a closer relationship with birds in Avialae (Senter 2007, Zhang et al. 2008), while other studies rejected a position in Avialae and placed them more distantly related to birds among basal paravian dinosaurs (Agnolin & Novas 2011, Godefroit et al. 2013, Brusatte et al. 2014, Lefèvre et al. 2014, Sorkin 2020). Several studies even recovered them among oviraptorid dinosaurs outside of Paraves (Agnolin & Novas 2013, O’Connor & Sullivan 2014; also see Headden 2013, Pittman & Xu 2020).

Against Darwinian Predictions

This scientific disagreement is mainly caused by the fact that the pattern of similarities does not unequivocally fall into a nested hierarchy, as would be predicted by Darwinism, but is highly incongruent. But the large degree of convergences is not restricted to similarities with different groups of dinosaurs but also includes characters of other vertebrate groups. “One of the most surprising of these is that of the scansoriopterygid (Theropoda, Maniraptora) Yi qi, which has membranous wings — a flight apparatus that was previously unknown among theropods but that is used by both the pterosaur and bat lineage” (Wang et al. 2019). The discovery by Xu et al. (2015) was so surprising that it was doubted by some experts (e.g., Padian 2015), but the discovery of a new taxon Ambopteryx longibrachium (Wang et al. 2019) strongly confirmed the findings.

The describers of Yi qi (Xu et al. 2015) concluded that “in having wings with a well-developed membranous component, Yi would differ from other volant paravians but resemble distantly related groups including pterosaurs, bats and many gliding mammals, representing a striking case of convergent evolution of the aerodynamic apparatus among tetrapods.” After the confirmation of membraneous wings in the new scansoriopterygid Ambopteryx, Milligan (2019) commented that “unlike other flying dinosaurs, namely birds, these two species have membranous wings supported by a rod-like wrist bone that is not found in any other dinosaur (but is present in pterosaurs and flying squirrels).” Consequently, “birds, it’s clear, weren’t the only flying dinosaurs — and these fossils reveal that flight itself, whether gliding or powered, evolved multiple times among them” (Gramling 2020). A new aerodynamic study by Dececchi et al. (2020) concluded that scansoriopterygids were a failed experiment in pre-bird theropod flight.

Evo-Babble and Convergence

Don’t let the evo-babble of convergent evolution fool you. Convergence is not evidence for evolution but conflicting evidence against evolution. It is incongruent data that do not fit with the Darwinian prediction of a nested hierarchy. Therefore, such incongruences have to be explained away with ad hoc hypotheses like homoplasy (convergence and/or secondary reduction), incomplete lineage sorting, hydridization, or horizontal gene transfer. Instead of admitting incongruent similarities as conflicting evidence, Darwinists hide this dirty secret with deceptive doublespeak like “convergent evolution.” Even though there are some similarities that are revealed as non-homologous by irreconcilable structural and/or genetic differences, most assumed convergences are just interpretations or rather rationalisations after the fact. It is not like the structure has a label that says “I am a convergence” but rather it is a corollary of the assumed correct tree of life and the optimization of characters on this tree. The latter procedure means that the principle of parsimony is used to minimize the number of gains and losses of a character that have to be assumed to plot its distribution on a given tree. If the distribution of the similarities is not congruent with the nested hierarchy of the tree, then multiple gains (convergence) or multiple losses (reduction) of the character have to be postulated. This is crucial and cannot be emphasized enough: Convergences are not observed, they are postulated (compare Kluge 1999 who defined homoplasy nominally as an operational error)!

Here is a thought experiment to expose the trickery: you’ve probably heard about the example of bat wings and bird wings as a paradigmatic showcase of convergent evolution. This is because both groups have transformed the tetrapod foreleg into wings, but are not closely related. Each is nested deeply within different non-volant tetrapod groups with normally developed legs, so that the wings cannot be interpreted as homologous and inherited from an assumed winged common ancestor. Now imagine the counterfactual case that the majority of evidence (e.g., from comparative morphology and phylogenomics) would rather suggest that birds and bats were closest relatives (so-called sister groups). Suddenly the assumed convergence would of course be interpreted as a shared derived character that was inherited from a winged bat+bird ancestor as a homology (synapomorphy). The differences between both wing constructions would be explained away as autapomorphic specializations from a common ground plan, and biologists would emphasize that birds don’t just have feathered wings, but that beneath the feathers you can find small wing membranes (so-called patagia) that would be considered as homologous to the wing membrane of bats. With the discovery of the membraneous scanosoriopterygid wings, evolutionists would have celebrated the discovery of a predicted transitional form that proves the reconstructed ground plan and provides an indisputable confirmation of the evolutionary scenario linking bats and birds. Only science deniers would doubt such an obvious established fact of evolution, right?

How Darwinists Reason

However, since birds and bats are not considered as closely related in the actual world, because birds cluster with dinosaurs and bats within mammals, their wings are interpreted as convergent. Likewise, the membraneous wings of scansoriopterygids are interpreted as another convergence, which would make vertebrate wings originate four times independently in pterosaurs, scansoriopterygids, birds, and bats. Darwinists do not really reason from the evidence to a hypothesis, as all good science should do, but only (re)interpret the evidence on the basis of their hypothesis, which therefore is immune to any challenge by conflicting data. When critics of intelligent design claim that it is not falsifiable, they are not only wrong (ID does make very specific testable predictions), but miss the inconvenient truth that it is Darwinism that is not falsifiable and thus of questionable scientific status.

The eminent philosopher of science Karl Popper explicitly recognized this until he was silenced and pushed to recant (Popper 1978: 345) by the Darwinist thought police. Here is what Popper (1976: 151 and 168) had said: “… because I intend to argue that the theory of natural selection is not a testable scientific theory, but a metaphysical research programme; … I have come to the conclusion that Darwinism is not a testable scientific theory, but a metaphysical research programme …” But even more interesting is what Popper (1957: 106) had said: “What we call the evolutionary hypothesis is an explanation of a host of biological and paleontological observations — for instance, of certain similarities between various species and genera — by the assumption of common ancestry of related forms.” (Emphasis added.) Read that carefully again. Did the penny drop? Common descent is assumed and the evidence interpreted accordingly, rather than common descent being deduced from the evidence. Common descent is the only conceivable materialistic option and thus considered as an unquestionable axiom. It may well be true, but it is hardly proven by this kind of dubious science.

References