DinoDex
Stocky beaked dinosaur with a bony neck frill and a tail fringe walking to the left
Life restoration of Protoceratops andrewsi from the Djadokhta Formation of Mongolia.Image credit: PaleoNeolitic, CC BY 4.0, via Wikimedia CommonsCC BY 4.0Source (opens in a new tab)

Protoceratops andrewsi

Pronounced PRO-toh-SERR-ah-tops AN-droo-zye

Ceratopsia · Protoceratopsidae

A sheep-sized horned dinosaur with a large frill and a parrot-like beak from the Late Cretaceous Gobi Desert of Mongolia. Hundreds of skeletons are known, including one locked in combat with a Velociraptor.

  • Quadrupedal
  • Eggs known
  • Famous specimen
Compare
Period
Cretaceous· Campanian
Diet
Herbivore
Length
2–2.5 m
Mass
62–104 kg
Location
Ömnögovi Province, Mongolia, Asia

Quick answers

How big was Protoceratops andrewsi?
Protoceratops andrewsi was about 2–2.5 m long. It stood about 0.6–0.8 m tall at the hips. It weighed about 62–104 kg. (Wikipedia: Protoceratops 2026; Paul 2016)
When did Protoceratops andrewsi live?
Protoceratops andrewsi lived during the Late Cretaceous, about 75–71 million years ago. (Paleobiology Database: Protoceratops andrewsi… 2026; Dashzeveg et al. 2005)
Where have Protoceratops andrewsi fossils been found?
Fossils of Protoceratops andrewsi have been found in Djadokhta Formation (Ömnögovi Province) and Mongolia. (Granger & Gregory 1923; Hone et al. 2016)
What did Protoceratops andrewsi eat?
Protoceratops andrewsi was a herbivore. (Granger & Gregory 1923; Hone et al. 2016)
Who named Protoceratops andrewsi, and when?
Protoceratops andrewsi was described by Walter Granger & William K. Gregory in 1923. (Granger & Gregory 1923; Paleobiology Database: Protoceratops andrewsi… 2026)

On this page

PRO-toh-SERR-ah-tops AN-droo-zye

Period
Cretaceous75–71 Ma
Diet
Herbivore
Length
2–2.5 m
Mass
0.1–0.1 t
Location
Mongolia, Asia
Classification
Ceratopsia · Protoceratopsidae
Described
1923, Walter Granger & William K. Gregory

Overview

Protoceratops andrewsi lived among the sand dunes of the Djadokhta Formation in what is now the Gobi Desert of Mongolia, in the Late Cretaceous. The photographer James B. Shackelford of the American Museum's Central Asiatic Expedition found the first skull at the Flaming Cliffs (Shabarakh Usu) in 1922, and Walter Granger and William K. Gregory named it in 1923 after the expedition leader Roy Chapman Andrews.

It was an early relative of the large horned dinosaurs, about 2 m long, with a big head, a bony frill and a small bump in place of a nose horn. The frill and nasal bump grew faster than the rest of the body as the animal matured, which suggests they were used as social or sexual signals (Hone et al. 2016).

Protoceratops is one of the best known dinosaurs, with many skeletons from hatchlings to adults. Its eggs were originally soft-shelled (Norell et al. 2020), and the famous "Fighting Dinosaurs" specimen preserves one locked in combat with Velociraptor.

Name meaning

"First horned face", from Greek protos, keras and ops; andrewsi after Roy Chapman Andrews, leader of the Central Asiatic Expeditions (Granger & Gregory 1923).

Biology & evidence

What scientists think about how this animal lived, and how strong the evidence for each idea is.

Eggs

  • Protoceratops laid soft-shelled eggs.

    Evidence level: Strong evidence

    The eggshells were originally organic, not mineralised, and resemble the soft eggshells of some turtles.

    Evidence for / against · 1
    Evidence for

    • Specimen · Protoceratops eggshell chemistry and histology

      Raman spectra and histology of exceptionally preserved Protoceratops eggs cluster them with soft, non-mineralised eggshells.

Behavior

  • The frill of Protoceratops was a social or sexual signal.

    Evidence level: Hypothesis

    Structures that grow disproportionately as an animal matures are typical of signals; other uses, such as anchoring jaw muscles, are not ruled out.

    Evidence for / against · 1
    Evidence for

    • Comparative anatomy · Protoceratops frill and nasal allometry

      Frill and nasal boss grow faster than the rest of the skull through growth (positive allometry).

Other

  • Protoceratops was prey of Velociraptor.

    Evidence level: Direct evidence

    The Fighting Dinosaurs show the two in combat, and Velociraptor tooth marks on Protoceratops bones show feeding.

    Evidence for / against · 1
    Evidence for

    • Specimen · Fighting Dinosaurs specimen

      A Velociraptor and a Protoceratops buried in the middle of a fight; the raptor's sickle claw is at the neck of its prey, whose jaws grip the raptor's arm.

      Specimen: MPC-D 100/25 “Fighting Dinosaurs”

Size

Length
2–2.5 m

(8.2 ft)

Height
0.7 mpublished range 0.6–0.8 m

(2.3 ft)

Based on adults

Mass
62–104 kg
Protoceratops andrewsi was about 2.5 m (8.2 ft) long, roughly 1.4 times the height of a 1.8 m adult human.

Timeline

Lived from about 75 to 71 million years ago (Ma), within the Mesozoic era (252–66 Ma).

Periods: Campanian (83.6–72.1 Ma), Late Cretaceous (100.5–66 Ma)

Djadokhta Formation, about 75-71 Ma: magnetostratigraphy suggests, without clearly establishing, deposition during the late Campanian polarity changes (Dashzeveg et al. 2005). PBDB bins the type collection in the whole late Campanian (83.6-72.2 Ma).

Location

Formations

Map data: Natural Earth (public domain). Modern positions, not where the continents were then.

These are the places where fossils have been found, not the full area where the animal lived.

Ecosystem

Djadokhta Formation scene with Velociraptor mongoliensis attacking Protoceratops andrewsi near a nest, with Shuvuuia deserti.Image credit: ABelov2014, CC BY 3.0, via Wikimedia CommonsCC BY 3.0Source (opens in a new tab)

Lived in: Djadokhta

75–71 million years ago · desert / dunes, other

An arid landscape of sand dunes and interdune areas in the Late Cretaceous Gobi, with occasional water. Sandslides and dune collapses buried animals alive, preserving articulated skeletons and nests.

Same ecosystem

Velociraptor mongoliensis

Cretaceous· CampanianCarnivore

Same ecosystem

Oviraptor philoceratops

Cretaceous· CampanianOmnivore

Classification

  1. cladeDinosauria
  2. cladeOrnithischia
  3. cladeCeratopsia
  4. familyProtoceratopsidae
  5. genusProtoceratops
  6. speciesProtoceratops andrewsi

Taxonomic status: Valid

Fossil record

Protoceratops skeleton FMNH PR 14064 on display at the Field Museum of Natural History, Chicago.Image credit: Evolutionnumber9, CC BY-SA 4.0, via Wikimedia Commons (unmodified except resizing), Field Museum of Natural HistoryCC BY-SA 4.0 (unmodified)Source (opens in a new tab)
Specimens
Catalog numberStatusInstitutionFound
AMNH 6251HolotypeAmerican Museum of Natural History (AMNH)1922

What has been found

Holotype: AMNH 6251

  • Preserved
  • Partial
  • Reconstructed
  • Unknown / not recorded
Region by region (table)
Skeleton regions of Holotype: AMNH 6251
RegionState
SkullPartial
MandibleUnknown / not recorded
TeethUnknown / not recorded
Cervical vertebraeUnknown / not recorded
Dorsal vertebraeUnknown / not recorded
SacrumUnknown / not recorded
Caudal vertebraeUnknown / not recorded
RibsUnknown / not recorded
GastraliaUnknown / not recorded
Scapula / shoulder girdleUnknown / not recorded
HumerusUnknown / not recorded
Forearm (radius / ulna)Unknown / not recorded
Hand (manus)Unknown / not recorded
PelvisUnknown / not recorded
FemurUnknown / not recorded
Tibia / fibulaUnknown / not recorded
Foot (pes)Unknown / not recorded

All specimens

Discovery

Year described
1923
Described by
Walter Granger & William K. Gregory
Type specimen
AMNH 6251

Discovery timeline

  1. 1922 · First material found

    Shackelford finds the first Protoceratops skull

    The expedition photographer spots a small skull at the Flaming Cliffs.

    People: James B. Shackelford, Roy Chapman Andrews

  2. 1923 · Formally described

    Granger and Gregory name Protoceratops andrewsi

    Named as a "pre-ceratopsian" in American Museum Novitates.

    People: Walter Granger, William K. Gregory

  3. 2020 · Major study

    Protoceratops eggs shown to be soft-shelled

    Norell and colleagues show the first dinosaur eggs were soft.

    People: Mark A. Norell

Sources

  1. (2026). Paleobiology Database: Protoceratops andrewsi occurrences and type collection 46152. The Paleobiology Database (paleobiodb.org), data service 1.2, accessed 2026-09-23. https://paleobiodb.org/data1.2/occs/list.txt?taxon_name=Protoceratops%20andrewsi&show=coords,paleoloc,strat,loc,ref&pgm=gplates (opens in a new tab)
  2. (2026). Wikipedia: Protoceratops. Wikipedia (English), accessed 2026-09-24. https://en.wikipedia.org/wiki/Protoceratops (opens in a new tab)
  3. Dashzeveg, D., Dingus, L., Loope, D. B., Swisher, C. C., III, Dulam, T. & Sweeney, M. R. (2005). New stratigraphic subdivision, depositional environment, and age estimate for the Upper Cretaceous Djadokhta Formation, southern Ulan Nur Basin, Mongolia. American Museum Novitates 3498: 1-31. https://digitallibrary.amnh.org/server/api/core/bitstreams/0df4baac-12e4-44ae-8ef7-3328b22e8604/content (opens in a new tab)
  4. Granger, W. & Gregory, W. K. (1923). Protoceratops andrewsi, a pre-ceratopsian dinosaur from Mongolia, with an appendix on the structural relationships of the Protoceratops beds. American Museum Novitates 72: 1-9.
  5. Hone, D. W. E., Wood, D. & Knell, R. J. (2016). Positive allometry for exaggerated structures in the ceratopsian dinosaur Protoceratops andrewsi supports socio-sexual signaling. Palaeontologia Electronica 19.1.5A. doi:10.26879/591 (opens in a new tab)
  6. Norell, M. A., Wiemann, J., Fabbri, M., Yu, C., Marsicano, C. A., Moore-Nall, A., Varricchio, D. J., Pol, D. & Zelenitsky, D. K. (2020). The first dinosaur egg was soft. Nature 583: 406-410. doi:10.1038/s41586-020-2412-8 (opens in a new tab)
  7. Paul, G. S. (2016). The Princeton Field Guide to Dinosaurs (2nd edition). Princeton University Press.