Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2014 May 7;281(1785):20140497.
doi: 10.1098/rspb.2014.0497. Print 2014 Jun 22.

Morphological and functional diversity in therizinosaur claws and the implications for theropod claw evolution

Stephan Lautenschlager  1
Affiliations

Morphological and functional diversity in therizinosaur claws and the implications for theropod claw evolution

Stephan Lautenschlager. Proc Biol Sci. .

Abstract

Therizinosaurs are a group of herbivorous theropod dinosaurs from the Cretaceous of North America and Asia, best known for their iconically large and elongate manual claws. However, among Therizinosauria, ungual morphology is highly variable, reflecting a general trend found in derived theropod dinosaurs (Maniraptoriformes). A combined approach of shape analysis to characterize changes in manual ungual morphology across theropods and finite-element analysis to assess the biomechanical properties of different ungual shapes in therizinosaurs reveals a functional diversity related to ungual morphology. While some therizinosaur taxa used their claws in a generalist fashion, other taxa were functionally adapted to use the claws as grasping hooks during foraging. Results further indicate that maniraptoriform dinosaurs deviated from the plesiomorphic theropod ungual morphology resulting in increased functional diversity. This trend parallels modifications of the cranial skeleton in derived theropods in response to dietary adaptation, suggesting that dietary diversification was a major driver for morphological and functional disparity in theropod evolution.

Keywords: Theropoda; finite-element analysis; functional morphology; shape analysis.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Manual unguals of Therizinosauria shown in lateral outline illustrating the large morphological variability across the group. Phylogeny based on the study of Zanno [4].
Figure 2.
Figure 2.
Two-dimensional morphospace plots of manual ungual shape based on first two principal component axes for the (a) combined theropod/mammal dataset and for (b) theropods only. (Online version in colour.)
Figure 3.
Figure 3.
Comparison of Von Mises stress distribution in different therizinosaurian taxa subjected to different functional scenarios. Unguals scaled to same surface area. Contour plots scaled to 150 MPa peak stress. Arrows symbolize applied forces. (Online version in colour.)
See this image and copyright information in PMC

References

    1. Clark JM, Maryanska T, Barsbold R. 2004. Therizinosauroidea. In The Dinosauria (second edition) (eds Weishampel DB, Dodson P, Osmolska H.), pp. 151–164. Berkeley, CA: University of California Press.
    1. Barsbold R. 1976. New data on Therizinosaurus (Therizinosauridae, Theropoda). Transactions, Joint Soviet–Mongolian Paleontological Expedition 3, 76–92. [In Russian.]
    1. Zanno LE. 2006. The pectoral girdle and forelimb of the primitive therizinosauroid Falcarius utahensis (Theropoda, Maniraptora): analyzing evolutionary trends within Therizinosauroidea. J. Vertebrate Paleontol. 26, 635–650. (10.1671/0272-4634(2006)26[636:TPGAFO]2.0.CO;2) - DOI
    1. Zanno LE. 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). J. Syst. Palaeontol. 8, 503–543. (10.1080/14772019.2010.488045) - DOI
    1. Paul GS. 1984. The segnosaurian dinosaurs: relics of the prosauropod–ornithischian transition? J. Vertebrate Paleontol. 4, 507–515. (10.1080/02724634.1984.10012026) - DOI

Publication types

LinkOut - more resources