Discussion of Character Analysis of the Appendicular Anatomy in Campanian and Maastrichtian North American Hadrosaurids—Variation and Ontogeny

Abstract

Over 50 morphological characters commonly have been used for defining and diagnosing the hadrosaurids, and these are reevalu ated in terms of data from ontogeny, paleopathology, and postcra nial studies. Features once used to define supraspecific taxa are also reevaluated in the light of population and ontogenetic variation.The hadrosaur postcranium becomes more robust with age, ex pressed as more rugose muscular attachments and greater deposi tion of bone on articular surfaces. Most ridges and bumps on the long bones are smooth, short, and do not project far from the shafts in small specimens. In the largest animals, ridges may be come exaggerated, and trochanters and muscular insertion scars become large, pitted, and rugose, with a tendency to look patho logical.Four size classes in hadrosaurids are identified on the basis of gross morphology that may reflect individual age. The first class (hatchling) represents hadrosaurids with little or no expansion of the muzzle, small and smooth articular surfaces, five or six sacrals, and less than 20 tooth rows. Over 50 morphological characters commonly have been used for defining and diagnosing the hadrosaurids, and these are devaluated in terms of data from ontogeny, paleopathology, and postcranial studies. Features once used to define supraspecific taxa are also reevaluated in the light of population and ontogenetic variation. The hadrosaur postcranium becomes more robust with age, expressed as more rugose muscular attachments and greater deposition of bone on articular surfaces. Most ridges and bumps on the long bones are smooth, short, and do not project far from the shafts in small specimens. In the largest animals, ridges may become exaggerated, and trochanters and muscular insertion scars become large, pitted, and rugose, with a tendency to look pathological.Four size classes in hadrosaurids are identified on the basis of gross morphology that may reflect individual age. The first class (hatchling) represents hadrosaurids with little or no expansion of the muzzle, small and smooth articular surfaces, five or six sacrals, and less than 20 tooth rows. The second class (juvenile) has a nu I" Brett-Surman, M. K. and J. R. Wagner. 2007. Discussion of character analysis of the appendicular anatomy in Campanian and Maastrichtian North American hadrosaurids-variation and ontogeny, pp. 135-169. In K. Carpenter (ed.), Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs. Indiana University Press, Bloomington.ticeable mu zzle, 20 to 40 tooth rows , articulations with so me r u gosities on the long bon es, six or seve n sacrals, and in t he Lam beosaurinae, th e appearance of inc ipient cranial cr ests and an is chial foot. (Loss of the ischial "foot" is a derived co nd ition .) The third size class (adult) is th e size ra nge in which all of the features useful fo r di agn osis of ha drosaurs are full y developed. The fo urth class (old age ) is characteri zed by 10 or more sacrals, all bony pro jections grea tly increased in size an d ru gosit y, fusion of t he ...

Mineralized soft-tissue structure and chemistry in a mummified hadrosaur from the Hell Creek Formation, North Dakota (USA)

“…The specimen MRF-03 of the Marmarth Research Foundation is tentatively assigned to approximately Edmontosaurus sp., based on the osteology of the pelvic and pectoral regions (Brett-Surman & Wagner 2007). However, this will be confirmed when preparation of the specimen is completed.…”

Perinates of a new species of Iguanodon (Ornithischia: Ornithopoda) from the lower Barremian of Galve (Teruel, Spain)

“…In the I. galvensis adult and perinates, the proximal plate resembles that of I. bernissartensis. However, the scapular blade is only preserved in the perinates (all show a slightly distal expansion similar to that seen in I. bernissartensis); this trait has been reported ontogenetically variable in other iguanodontians (Brett-Surman and Wagner, 2007;Hübner, 2011;Prieto-M arquez, 2011Prieto-M arquez, , 2014Guenther, 2014). Holotype.…”

“…4F). Few ontogenetic changes in the shape of the ilium have been reported for iguanodontians (Brett-Surman and Wagner, 2007;Hübner, 2011;Guenther, 2014;Prieto-M arquez, 2014). In I. galvensis, the preacetabular process curves ventrally while in I. bernissartensis it is straight and deflects ventrally, forming, in lateral view, an obtuse angle between the dorsal margin of the body of the ilium and the preacetabular process (Fig.…”

“…In hadrosaurids, the immature pubis resembles that of the adult (Brett-Surman and Wagner, 2007;Prieto-M arquez, 2014). The prepubic ramus of the I. galvensis perinates (Figs.…”

“…This resulted in a matrix with dimensions of 68 x 135 (68 operational taxonomic units [OTUs] with 135 cranial and postcranial codifying characters each). For I. galvensis, 59 characters (cranial and postcranial) were codified using the information from the holotype and the referred material, taking into account only those derived and non-ontogenetically variable characters present in the juvenile and perinates (Brett-Surman and Wagner, 2007;Hübner, 2011;Prieto-M arquez, 2011Prieto-M arquez, , 2014Guenther, 2014). With the addition of these, the TAXEQ3 program (Wilkinson, 2001a) detected 5283 missing entries (57.5% non-codified characters).…”