Evolutionary Teratology and the Path to Break Through the Mould of the Synthesis Paradigm

The forelimbs of Alvarezsauroidea (Dinosauria: Theropoda): Insight from evolutionary teratology

“…The lack of certainty regarding the As previously mentioned, the diagnostic ratio for forelimb size falls below the predetermined threshold (0.526). Shuvuuia is thus included in the micromelic spectrum (Guinard 2020a(Guinard , 2020b. Macrodactyly of digit I is accompanied by a drastic decrease in the proportion of digits II and III (S. Suzuki et al, 2002), compared to Haplocheirus (Figure 3).…”

“…Beyond this feature, in fine, the avian wing forms only three digits and only the one in position 4 (i.e., digit III) is derived from Shhexpressing cells (Zeller et al, 2009). By extension, this conserved molecular and developmental process is transposable to the evolutionary trajectory of theropods in the manual loss of posterior digits (Guinard, 2015(Guinard, , 2020a(Guinard, , 2020b.…”

“…As such, evolutionary teratologies are variations identified as developmental anomalies, with the evo-devo connection providing a means of exposing their possible causes. Evolutionary teratology is a diagnosis that puts anatomical structure and its nature back at the centre of multidisciplinary epistemological reasoning (Guinard, 2020b). The diagnosis, whether quantitative (loss of anatomical elements) or qualitative (drastic variation in the anatomical proportion of an organ), or both, is superimposed on the phylogeny of the groups concerned, but is not intended to substitute for these reconstructions-the particular nature of the diagnosis is a complement to the links established via the variety of known anatomical characters (Figure 2).…”

“…Identification of evolutionary teratologies within a group of nonavian theropod dinosaurs: Tyrannosauroidea—anomalous variations are quantitative (losses of manual elements) and qualitative (drastic reduction in the forelimb proportion), following morphological data from Xu et al, 2004; Xu et al, 2006, and diagnosis from Guinard, 2015, 2020b.…”

“…Alvarezsauroidea. For the record, anterior micromelia is an anatomical condition identified when the length of the humerus + radius + longest metacarpus (MTC) set is less than two-thirds the length of the F I G U R E 2 Identification of evolutionary teratologies within a group of nonavian theropod dinosaurs: Tyrannosauroidea-anomalous variations are quantitative (losses of manual elements) and qualitative (drastic reduction in the forelimb proportion), following morphological data fromXu et al, 2004;Xu et al, 2006, and diagnosis from Guinard, 2015, 2020b …”