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Edited by Steven M. Stanley, University of Hawaii, Honolulu, HI, and approved March 31, 2010 (received for review January 20, 2010)
Article Figures & SI
Figures
- Fig. 1.
Photographs of some of the sampled titanosaur bones from the Maastrichtian of Romania. (A–D) Magyarosaurus dacus humeri, specimens (A) MAFI Ob. 3092 (smallest recorded body size, 45% maximum size), (B) FGGUB R.1246 (65% maximum size), (C) MAFI v.13492 (76% maximum size), (D) FGGUB R.1048 (largest known specimen), and (E) “Magyarosaurus” hungaricus, MAFI Ob.3104. (Scale bar, 100 mm.)
- Fig. 2.
Micrographs of long bone histology. (A–E) Long bone histology of Magyarosaurus dacus under crossed polarizers. (A) Micrograph of a midshaft section of the smallest available specimen of Magyarosaurus dacus (MAFI Ob.3092, 46% max size). (B) Close-up of A: largely interstitial laminar primary bone in the outermost cortex. The vascular canals are oriented circumferentially as in laminar fibrolamellar bone, but the bone matrix between the vascular canals consists largely of parallel-fibered and lamellar bone, with only a minute fraction of fibrous (or woven) bone tissue. (C) Micrograph of a midshaft section of MAFI v.13492 (76% max. size). The cortex is completely remodeled, in some areas several generations of secondary osteons can be seen crosscutting each other. (D) Closeup of C: cortex dominated by several generations of secondary remodeling. (E) Micrograph of a midshaft section of the largest available M. dacus humerus (FGGUB R.1048). (F) Close-up of E: Note the secondary osteons of the third generation, and truncated secondary osteons at the outer bone surface. (G and H) Long bone histology of ‘M.’ hungaricus under polarized light. (G) Micrograph of a midshaft section of ‘M.’ hungaricus (MAFI Ob.3104). The specimen is strongly remodeled, but the interstitial primary tissue is of the highly vascularized laminar fibrolamellar kind, with well developed primary osteons in the middle cortex, and poorly developed primary osteons with no lamellar bone infilling in the outermost cortex. Note that secondary osteons of the first generation are less well developed than in the largest M. dacus specimens. (H) Close-up of G: Secondary osteons crosscutting well developed primary osteons in the middle cortex. (I) Laminar fibrolamellar bone of Apatosaurus (BYU 72517014). (J) Alligator (SMNS 10481) long bone histology showing lamellar-zonal bone. (Scale bars: A, B, and D–H, 200 μm; C, 1,000 μm; I and J, 500 μm).
- Fig. 3.
Plot of histologic ontogenetic stage (HOS) (35) vs. body size as expressed by femur length in Magyarosaurus dacus, compared with Europasaurus, Apatosaurus, Alamosaurus, and Phuwiangosaurus. The samples of Magyarosaurus dacus derive from humeri that were normalized to femur length. The single “M”' hungaricus sample is also included. Data for Alamosaurus were obtained from a previous report (38), supported by own data. Data for Phuwiangosaurus were obtained from another report (37).
Tables
Specimen Collection Locality Taxon Bone type Side Length (mm) Minimal shaft circumference (mm) Percentage maximum size Standardized length (to humerus) Standardized percentage maximum size HOS R.1220 FGGUB Groapa Magyarosaurus Femur R (346) 176 64 266 54.5 13 R.1511 FGGUB Groapa Magyarosaurus Femur L (466) 179 86 358 73 13 R.1046 FGGUB Ciula Magyarosaurus Femur L 525 193 97 403.5 82.5 14 R.1992 FGGUB Ciula Magyarosaurus Femur R (540) 195 100 414.5 85 14 Ob.3092 MAFI Vălioara Magyarosaurus Humerus L (222) 115 46 222.5 46 12 R.1246 FGGUB Groapa Magyarosaurus Humerus R (320) 122 65.5 320 65.5 14 R.1195 FGGUB Scoaba Titanosauria indet. (?Mag-yarosaurus) Humerus L (346) 150 71 346 71 13 Ob.3089 MAFI Vălioara Magyarosaurus Humerus L (365) 136 75 365 75 14 v.13492 MAFI Vălioara Magyarosaurus Humerus R 372 140 76 372 76 13 Ob.3128 MAFI Vălioara Magyarosaurus Humerus L (432) 151 88 432 88 14 R.1047 FGGUB Ciula Magyarosaurus Humerus R 403 183 82.5 403 82.5 13 R.1048 FGGUB Sînpetru Magyarosaurus Humerus L (488) 194 100 488 100 14 Ob.3104 MAFI Vălioara - Budurone “M.” hung-aricus Humerus R (914) 365 914 — 12 R.1252 FGGUB Groapa Magyarosaurus Tibia L (354) 105 79 — — 12 Ob.4212 MAFI Vălioara Magyarosaurus Tibia L (323) 109 72 — — 12.5 R.1380 FGGUB Cărare Magyarosaurus Tibia L (402) 134 89 — — 13 R.1045 FGGUB unknown Magyarosaurus Tibia R 450 181 100 — — 14 Ob.3087 MAFI Vălioara Magyarosaurus Tibia L (858) 260 — — 14 Ob.3086a MAFI Vălioara Magyarosaurus Fibula L (388) 100 — — 14 Ob.3086b MAFI Vălioara Magyarosaurus Fibula L (384) 101 — — 14 R.1598 FGGUB Groapa Magyarosaurus Ulna L (219) 95 65 — — 14 Ob.3099 MAFI Vălioara Magyarosaurus Ulna R 337 128 100 — — 14 Data in parentheses indicate estimated total length, provenance, relative size, and histologic ontogenetic stage (HOS). L, left; R, right.
Data supplements
Supporting Information
Files in this Data Supplement:
Small body size and extreme cortical bone remodeling indicate phyletic dwarfism in Magyarosaurus dacus (Sauropoda: Titanosauria)
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