croissance

Juvenile Gorgosaurus TMP 2009.12.14 preserving stomach contents. Photographs of specimen in (A) right lateral view and (B) left anterolateral view. (C) Interpretive illustration of specimen in right lateral view. Skeleton consists of a nearly complete skull, the left side of the body and limbs, and a nearly complete pelvis. Red rectangle delineates location of stomach contents. (D) Histological photomicrograph of tibia showing the presence of five lines of arrested growths and two annuli (marked by asterisks), indicating that the individual was between 5 and 7 years old. Scale bars, 50 cm (A) to (C) and 1 mm (D).

Osteohistology of UALVP 59606, metatarsal IV of Citipes elegans. Overview of histological thin section of UALVP 59606 in plane-polarized (A) and cross-polarized (B) light, showing locations of close-up images. Detail (C) of cortex showing predominantly primary fibrolamellar bone with longitudinal-reticular vascularity, endosteal layer, and cyclical growth marks (arrows), under plane-polarized light. Close-up (D) of well developed endosteal layer on the medullary cavity, showing sec- ondary excavation by simple vascular canals, under cross-polarized light. Close-up (E) of tightly packed cyclical growth marks (arrows) near the periosteal surface of the cortex, under plane-polarized light. Close-up (F) of periosteal surface of cortex, showing avascular parallel-fibered bone indicating an incipient external fundamental system (double ended arrow) with three LAGs (arrows). Abbreviations: efs, incipient external fundamental system; el, endosteal lamellae; hb, Haversian bone; pfb, parallel-fibered bone; radv, radial simple vascular canal; so, secondary osteon.