Project 836: A. A. Farke, D. J. Chok, A. Herrero, B. Scolieri, S. Werning. 2013. Ontogeny in the tube-crested dinosaur Parasaurolophus (Hadrosauridae) and heterochrony in hadrosaurids. PeerJ. 1 (e182):1-83.
Specimen: † Parasaurolophus (Parks, 1922) (RAM:14000)
View: Histology, tibia (right), section B, near mid-diaphysis (135mm from proximal end), cross-section


The tube-crested hadrosaurid dinosaur Parasaurolophus is remarkable for its unusual cranial ornamentation, but little is known about its growth and development, particularly relative to well-documented ontogenetic series for lambeosaurin hadrosaurids (such as Corythosaurus, Lambeosaurus, and Hypacrosaurus). The skull and skeleton of a juvenile Parasaurolophus from the late Campanian-aged (~ 75.5 Ma) Kaiparowits Formation of southern Utah, USA, represents the smallest and most complete specimen yet described for this taxon. The individual was approximately 2.5 m in body length (25% maximum adult body length) at death, with a skull measuring 246 mm long and a femur 329 mm long. A histological section of the tibia shows well vascularized, woven and parallel-fibered primary cortical bone typical of juvenile ornithopods. The histological section revealed no lines of arrested growth or annuli, suggesting the animal may have still been in its first year at the time of death. Impressions of the upper rhamphotheca are preserved in association with the skull, showing that the soft tissue component for the beak extended for some distance beyond the limits of the oral margin of the premaxilla. In marked contrast with the lengthy tube-like crest in adult Parasaurolophus, the crest of the juvenile specimen is low and hemicircular in profile, with an open premaxilla nasal fontanelle. Unlike juvenile lambeosaurins, the nasal passages occupy nearly the entirety of the crest in juvenile Parasaurolophus. Furthermore, Parasaurolophus initiated development of the crest at less than 25% maximum skull size, contrasting with 50% of maximum skull size in hadrosaurs such as Corythosaurus. This early development may correspond with the larger and more derived form of the crest in Parasaurolophus, as well as the close relationship between the crest and the respiratory system. In general, ornithischian dinosaurs formed bony cranial ornamentation at a relatively younger age and smaller size than seen in extant birds. This may reflect, at least in part, that ornithischians probably reached sexual maturity prior to somatic maturity, whereas birds become reproductively mature after reaching adult size.

Read the article »

Project DOI: 10.7934/P836,
This project contains
  • 25 Media
  • 1 Taxon
  • 1 Specimen
Total size of project's media files: 267.6M

Download Project SDD File
Currently Viewing:
MorphoBank Project 836

    Authors' Institutions

    • University of California Berkeley

    • Raymond Alf Museum of Paleontology (The Webb Schools)

    • The Webb Schools, Clarement, CA


    member name taxa specimens media media
    Sarah Werning
    Project Administrator
    MorphoBank Curator
    Full membership
    Andrew Farke
    Full membership

    Project has no matrices defined.

    Project views

    type number of views Individual items viewed (where applicable)
    Total project views47220
    Project overview6976
    Media views30118Media search (6627 views); M283543 (902 views); M283540 (912 views); M283554 (1004 views); M283550 (1003 views); M283552 (945 views); M151601 (1136 views); M193513 (928 views); M193515 (904 views); M283537 (917 views); M193511 (979 views); M193512 (918 views); M283541 (985 views); M283544 (956 views); M283551 (873 views); M283542 (916 views); M193514 (923 views); M283547 (938 views); M283553 (934 views); M283538 (936 views); M283539 (885 views); M283546 (912 views); M283549 (970 views); M283545 (892 views); M193522 (962 views); M283548 (861 views);
    Views for media list2071
    Specimen list3773
    Taxon list2795
    Documents list2

    Project downloads

    type number of downloads Individual items downloaded (where applicable)
    Total downloads from project443
    Project downloads427
    Media downloads16M193513 (2 downloads); M151601 (2 downloads); M283542 (1 download); M283549 (1 download); M283552 (1 download); M283554 (4 downloads); M193514 (1 download); M193515 (1 download); M283537 (2 downloads); M283550 (1 download);