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Blood Clots in Dinosaur Bones


fluvial systems with occasional catastrophic flooding resulting in some extinction [44,45]. If Triceratops in the Hell Creek Forma- tion drowned while suffering major tissue injury in a flooding event, the microvasculature within bones might be characterized by heavy clotting. Tis clotting could have inhibited the passage of water (required to maintain ongoing Fenton reactions) and could have sequestered free iron in RBCs within clots making it unavailable for the generation of hydroxyls and peroxyls. In this study we examined ground sections of Triceratops


bone for evidence of clotting and sequestration of iron in microvascular canals.


Methods Triceratops bones, including horn (HCTH-02, 03), rib


(HCTR-11), and vertebra (HCTV-22) previously collected within the Hell Creek Formation in Montana [1] were pro- cessed for ground thin sections of 80 µm thickness. Triceratops frill (HCTF-39), collected at the same location in 2015, was sim- ilarly processed. Microvascular canals were examined on non- coverslipped sections under a UV-fluorescence (Hund, Wetzlar Germany H500) microscope supplied with a 100 W mercury burner. Specimens were excited at UV wavelengths (254 nm, 366 nm), and autofluorescence images were captured with a ProgRes CF-cool (Jenoptik, Germany) low-light camera.


Figure 10a, 10b: Triceratops rib (HCTR-11). Clots in Haversian canals and an anastomosing canal (right of center). Some clearings are visible, but canals are mostly occluded. Under UV (10b), rib clots were not as organized as in horn and vertebra, and the brightly reflective layer is somewhat diffuse, less organized, and not abutted to canal walls. Scale bar, 100 μm.


show that acute mental stress can elevate hemoconcentration, plasma viscosity, lipid concentrations, and certain tissue clotting factors [42,43]. If enough platelets and clotting factors are avail- able, the clotting cascade will be maintained until resources are exhausted, but cellular death will interrupt the cascade. If death is averted, and as platelets are depleted, DIC can reverse, and sys- temic, untreatable bleeding might occur [39]. Tis is observed only in a low number of cases [40]. Interestingly, autopsy findings of human patients with overt DIC exhibited systemic clots through- out all small, medium, and large arteries and veins [40,41]. In the case of Triceratops animals buried at Hell Creek,


trauma and asphyxiation are suggested as the cause of death based on the specific fluvial architectural elements found there [44]. Te Hell Creek Formation in Glendive, MT (and surrounding areas) has been characterized as a low coastal plain with meandering


36


Figure 11a, 11b: Triceratops frill (HCTF-39). Clot with large central opening (asterisks). Note distinct outer dark margin line of clot, appressed to canal wall (black arrows, 11b). White arrows point to angular shards embedded within brightly reflective layer. Scale bar, 100 µm.


www.microscopy-today.com • 2020 September


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