Bone Microstructure Reflects Evolution of Large Size in Horned Dinosaurs

Abstract

Bone microstructure reflects the rate of bone tissue deposition. That hypothesis [1] was recently tested experimentally [2-4]. Rapidly growing bones have a greater proportion of vascular canals than slowly growing bones do. In addition, bones experiencing relatively high growth rates form radial vascular canals. Those radial canals radiate outwards from the periosteal surface and allow rapid increases in bone girth. Whether the deposition of radials canals plays a role in evolutionary increases in body size, however, remains untested.

Bone Laminarity in the Avian Forelimb Skeleton and Its Relationship to Flight Mode: Testing Functional Interpretations

“…Given that experimental data (Swartz et al, 1992; Biewener and Dial, 1995) have demonstrated that torsion and bending appear to be the dominant loading regimes on the humerus during flight, this study was developed around characterizing that morphology hypothesized to be directly related to torsion resistance (de Margerie 2002, de Margerie et al, 2005), thus LI was the chosen metric. However, future work may explore methods that fully characterize all potential canal orientations (i.e., radial, oblique, longitudinal and circular) (de Boef and Larsson, 2007; Lee, 2007).…”

“…The sample selected for this study was within one standard deviation from the mean LI of all samples. Although other methods have been developed for characterizing vascular canal organization in bone (e.g., see de Boef and Larsson, 2007; Lee, 2007), we have purposefully elected to employ the system developed by de Margerie (2002). Not only does this allow us to directly compare our data with published laminarity indices (de Margerie 2002; de Margerie et al, 2005), but it provides an explicit test of the relationship between LI and inferred loading patterns (e.g., resistance to torsion).…”

Filling in Gaps in the Ceratopsid Histologic Database: Histology of Two Basal Centrosaurines and an Assessment of the Utility of Rib Histology in the Ceratopsidae

“…Thus, Psittacosaurus may not be a good model for basal ceratopsian growth. Based on a somewhat smaller sample set, Lee () showed that Psittacosaurus and Protoceratops grew quickly in their first 2 years of life, marked by radial growth, and subsequently slowed down. Zhao et al .…”

“…In the case of ANS 15800, this could be related to the young age of the animal, but in the sub-adult or adult CPC 274, it is clear that cyclic changes in canal orientation were not present. Lee (2007) notes that Centrosaurus likely grew quickly for its first 3 years of life and then slowed down. Although it is not possible to assess the absolute age of ANS 15800 without multiple representatives of the species, it is likely that ANS 15800 was still in this initial fast-growing phase.…”

“…Thus, Psittacosaurus may not be a good model for basal ceratopsian growth. Based on a somewhat smaller sample set, Lee (2007) showed that Psittacosaurus and Protoceratops grew quickly in their first 2 years of life, marked by radial growth, and subsequently slowed down. Zhao et al (2016) further demonstrated that juvenile Psittacosaurus grew extremely quickly and had a combination of radial and reticular canals in the first year of life.…”