PLOS ONE2013-12-06 1:57 AM

The ‘Unicorn’ Dinosaur That Wasn’t: A New Reconstruction of the Crest of Tsintaosaurus and the Early Evolution of the Lambeosaurine Crest and Rostrum

Abstract
The lambeosaurine Tsintaosaurus spinorhinus has traditionally been reconstructed with an elevated, hollow, spike-like crest composed entirely of the nasal bones, although this has been disputed. Here, we provide a new reconstruction of the skull of this species based on reexamination and reinterpretation of the morphology and articular relationships of the type and Paratype skulls and a fragmentary crest. We confirm the presence of a supracranial crest composed of the elevated nasal bones, but also including the premaxillae. We hypothesize that the crest is a tall, lobate, hollow structure that projects dorsally and slightly caudally a distance greater than the height of the skull along the quadrate. In our reconstruction, the nasal passage passes through the crest, but enters the skull rostral to the tubular process of the nasals, not through it. Tsintaosaurus spinorhinus is rediagnosed on the basis of a suite of cranial autapomorphies including a circumnarial fossa subdivided into three accessory fossae, prefrontal with ascending rostral process and lateral flange, nasals fused sagittally to form elongate tubular process that rises dorsally from skull roof, each nasal being expanded rostrocaudally into a rhomboid distal process, and medial processes of premaxillae at the summit of the cranial crest inserted between rhomboid processes of nasals. Tsintaosaurus spinorhinus lacks characters that are present in more derived lambeosaurines (parasaurolophins and lambeosaurins), such as rotation of the caudal margin of the crest to an acute angle with the skull roof, lateral processes of the nasals that enclose part of the intracranial cavity and participate in the formation of the walls of the common median chamber, and a smooth narial fossa lacking ridges and accessory fossae. We hypothesize that ancestrally the rostrum of lambeosaurines may have been more similar to that in Saurolophinae, and became subsequently reduced in complexity during evolution of the group.

KEYWORDS

SHARE & LIKE

COMMENTS

ABOUT THE AUTHOR

PLOS ONE

0 Following 5 Fans 0 Projects 90 Articles

SIMILAR ARTICLES

AbstractAgencies that fund scientific research must choose: is it more effective to give large grants to a few elite researchers, or small grants to ma

Read More

Abstract The role of genetically modified (GM) crops for food security is the subject of public controversy. GM crops could contribute to food product

Read More

Abstract 论文摘要 Background Combination antiretroviral therapy (ART) has significantly increased survival among HIV-positive adults in the United State

Read More

AbstractThe U.S. National Institutes of Health (NIH) budget expansion from 1998 through 2003 increased demand for biomedical research, raising relative

Read More

Abstract Kawaii (a Japanese word meaning “cute”) things are popular because they produce positive feelings. However, their effect on behavior remains

Read More

Abstract The diversity of life is one of the most striking aspects of our planet; hence knowing how many species inhabit Earth is among the most funda

Read More

Abstract Lateralized brain regions subserve functions such as language and visuospatial processing. It has been conjectured that individuals may be le

Read More

Abstract Background and Aims Questions over the clinical significance of cannabis withdrawal have hindered its inclusion as a discrete cannabis ind

Read More