# Edmontosaurus annectens

> A large duck-billed dinosaur from the very end of the Cretaceous in western North America, a common plant-eater of the Hell Creek and Lance formations and prey of T. rex. Several "mummies" preserve its skin.

- Classification: Dinosauria (clade) > Ornithischia (clade) > Ornithopoda (clade) > Hadrosauridae (family) > Saurolophinae (subfamily) > Edmontosaurus (genus) > Edmontosaurus annectens (species)
- Length: 12–15 m
- Hip height: 2.6–3.4 m
- Mass: 5.6–15.9 t
- Age: 72.1–66 million years ago (Late Cretaceous)
- Fossils found in: Lance Formation (Wyoming); Hell Creek Formation (Montana); Frenchman Formation (Saskatchewan); United States; Canada
- Diet: herbivore
- Described: Othniel Charles Marsh, 1892

Canonical page: https://dinodex.club/dinosaurs/edmontosaurus-annectens
Last updated: 2026-09-27

## Overview

Edmontosaurus annectens lived in western North America in the late Maastrichtian, alongside Tyrannosaurus and Triceratops. Othniel Charles Marsh named it Claosaurus annectens in 1892 from a skeleton from the Lance Formation of Wyoming (USNM 2414). The genus Edmontosaurus had been named by Lawrence Lambe in 1917 for the older species E. regalis from Alberta.

It was a big, flat-headed hadrosaur that walked on four or two legs and chewed plants with batteries of hundreds of teeth. Several naturally mummified specimens, the first found by the Sternberg family in 1908, preserve large areas of scaly skin. Campione and Evans (2011) showed that the giant "Anatotitan" was just a large E. annectens, leaving two species in the genus.

A Tyrannosaurus tooth embedded in two fused, healed tail vertebrae of a hadrosaur like Edmontosaurus shows that T. rex attacked living animals and that this one escaped (DePalma et al. 2013).

## Name meaning

"Edmonton lizard", after the Edmonton Formation of Alberta where the type species was found (Lambe 1917); annectens, Latin for "connecting" (Marsh 1892).

## Sources

1. (2026). Paleobiology Database: Edmontosaurus occurrences. The Paleobiology Database (paleobiodb.org), data service 1.2, accessed 2026-09-23. https://paleobiodb.org/data1.2/occs/list.txt?base_name=Edmontosaurus&show=coords,paleoloc,strat,loc,ref&pgm=gplates
2. (2026). Wikipedia: Edmontosaurus. Wikipedia (English), accessed 2026-09-23. https://en.wikipedia.org/wiki/Edmontosaurus
3. Campione, N. E. & Evans, D. C. (2011). Cranial growth and variation in edmontosaurs (Dinosauria: Hadrosauridae): implications for latest Cretaceous megaherbivore diversity in North America. PLoS ONE 6: e25186. https://doi.org/10.1371/journal.pone.0025186
4. Cohen, K. M., Harper, D. A. T., Gibbard, P. L. & Car, N. (2023). International Chronostratigraphic Chart (v2023/09). International Commission on Stratigraphy. https://stratigraphy.org/ICSchart/ChronostratChart2023-09.pdf
5. DePalma, R. A., Burnham, D. A., Martin, L. D., Rothschild, B. M. & Larson, P. L. (2013). Physical evidence of predatory behavior in Tyrannosaurus rex. Proceedings of the National Academy of Sciences 110. https://doi.org/10.1073/pnas.1216534110
6. Lambe, L. M. (1917). A new genus and species of crestless hadrosaur from the Edmonton Formation of Alberta. The Ottawa Naturalist 31(7): 65-73.
7. Marsh, O. C. (1892). Notice of new reptiles from the Laramie Formation. American Journal of Science 43: 449-453.
8. Paul, G. S. (2016). The Princeton Field Guide to Dinosaurs (2nd edition). Princeton University Press.

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Cite as: "Edmontosaurus annectens". DinoDex. https://dinodex.club/dinosaurs/edmontosaurus-annectens (updated 2026-09-27).