an ankylosaur from the Late Cretaceous of China.

Trio [221 kb] Trio [337 kb]

Figs. 1-2: three superb specimens of Crichtonsaurus bohlini Dong, 2002), a small but heavily armoured ankylosaur, a compact, herbivorous dinosaur from the late Cretaceous of China. With adjacent specimen label. The specimens shown here are in the vertebrate palaeontology display of the Yifu Museum (Figs. 1-2,5-6) and the nearby National Library of Geology (Figs. 3-4) on the campus of CUGB, the China University of Geosciences - Beijing, Haidian campus. Photos taken April 2016, May 2016 (Figs. 3-4) and May 2017 (Figs. 5-6).

"Rock of the Month # 248, posted for February 2022" ---

Preface and disclaimer

Regular viewers of the "Rock of the Month" know I am a geologist and something of a mineralogist, but not a palaeontologist! Especially, not a vertebrate anatomist. Still, in the interests of diversity, this is the fourth vertebrate addition to the series, and the only real dinosaur. So hopefully this entry - or at least the photographs - will be of interest, even though I cannot vouch for the finer details in the text (myself, I prefer the genus "Bibliosaurus" for Figs. 3-4!). At the least, the museum display is impressive, and delights the visiting students. My layman status in this bony subject explains why many of the following references are from the determinedly generalist publication of the Geological Association of Canada, the Canadian Journal of Earth Sciences ("CJES"). I hope this modest dig into the paleo scriptures sheds some light on these interesting specimens. Next month I will return to rocks, where I feel on more, er, solid ground!

Armoured dinosaurs, and other fascinating stuff

The popularity of dinosaurs, not just with specialists but with children of all ages, has led to a major publishing industry. There are some excellent books which outline many of the dinosaur families throughout the Mesozoic era, and their global distribution (see, e.g., Lambert et al., 1998; Norman, 1991).


Ankylosaurs and related forms, such as nodosaurs, are a lineage of herbivorous armoured dinosaurs that lived in the Jurassic and Cretaceous periods. Ankylosaurs sported heavy tail clubs, absent in the earlier nodosaurs. The ankylosaurs and their relatives flourished in the Cretaceous, from early (nodosaur) forms to the latest (including some of the largest) ankylosaurs, through to the latest Cretaceous time. The fossil record seems especially rich in western North America and southeast Asia (China and Mongolia). Ankylosaur remains are also reported from the eastern Indian state of Andhra Pradesh (Nath et al., 2002).

There is a history of exciting dinosaur finds in China, in part related to Sino-Soviet expeditions in 1959-1960 (Vickaryous et al., 2001). Further progress was made by the expeditions of the China-Canada dinosaur project (Cumbaa et al., 2021, pp.735-737) to Xinjiang, Liaoning and other parts of China, senior members of which include Dale Russell of the Canadian Museum of Nature and colleague Dong Zhiming.

Research in China has advanced descriptions of the genus Crichtonsaurus, in at least two species (Dong, 2002; Liu et al., 2011). The existence of numerous specimens seems beyond doubt, but the recognition or definition of the genus Crichtonsaurus apparently has some technical problems. Maybe some experts may be tempted to place these beasts in the paleo-trashcan of puzzling lifeforms labelled Problematica, the name a Nomen dubium! Why is this? Indirectly, I am going to dodge this question, since it is entirely above my pay grade! Clues, at least, can be found in a Wikipedia entry (viewed 04 December 2021) which provides more specific detail on the taxonomy and research on Crichtonsaurus:

"The first fossils of the genus were discovered in 1999 in the Sunjiawan Formation of Xiafuxiang, near Beipiao in Liaoning Province, China. It was named and described by Dong Zhiming of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences in 2002. The type species is Crichtonsaurus bohlini". The genus is named for author Michael Crichton, while the specific name honours Birger Bohlin, "a Swedish paleontologist who during the 1930s took part in several paleontological expeditions to China. He described numerous Chinese ankylosaurs". The initial descriptions of Crichtonsaurus may have worked with a rather scanty trove of material, itemized in the Wiki article.

I am not sure whether subsequent finds, such as the apparently complete skeletons to be seen at CUGB (Anon, 2016) and other Chinese universities and museums, have been much examined by western workers. Nor can I be sure how much of the material is complete, and how much of the display specimens may perhaps be reconstructed from partial skeletal remains. However, the second species Crichtonsaurus benxiensis, has been moved to a distinct genus of its own, Crichtonpelta (Arbour and Currie, 2015), leaving the original C. bohlini as a single-species show of its own.

North America

Ankylosaur genera and their anatomy have been described from Alberta and Montana (e.g., Coombs, 1995; Carpenter, 2004; Parsons and Parsons, 2009; Penkalski and Blows, 2013). Henderson and Tanke (2010) offer a statistical analysis of the trove of ankylosaur and other dinosaur fossils recovered now (and hopefully in future) from the productive strata of Dinosaur provincial park in Alberta.

A paleogeographic reconstruction of North America in the Mesozoic helps explain the environments where these creatures lived (Graves, 1993).

Bibliosaurus [234 kb] Bibliosaurus [221 kb]

Figs. 3-4: another specimen of Crichtonsaurus graces the entrance hall of the National Library of Geology on the CUGB campus in Haidian district, Beijing.

Trio [291 kb] Trio [232 kb]

Figs. 5-6: back at the Yifu Museum, two more views of the trio of skeletons.

There are some plants extant today that could well have been, if not browsed, then perhaps trampled by a passing ankylosaur. An example are wetland plants of the genus Equisetum. These have been documented, e.g., in the lower Cretaceous of Gansu in northwest China (Sun et al., 2013). Today, in my backyard in southern Ontario, it is common to find the smooth scouring rush (Equisetum laevigatum) along the banks of streams or beside ponds and areas of restricted drainage that are more or less permanently waterlogged (Fig. 7). The preservation of Equisetum fossils in the lower Cretaceous Zhonggou Formation, in the Jiuquan basin of Gansu, highlights a freshwater environment of that time, probably a riverbank setting in a generally arid region (Sun et al., 2013).

Equisetum [495 kb]

Fig. 7. A thick stand of smooth scouring rush, a modern Equisetum species, on the right bank of Trout Creek, in the Trent River watershed west of Campbellford, southeast Ontario, 03 December 2021. I had wondered whether ankylosaurs might graze on such contemporary plants, but I have it on sound advice that ankylosaur teeth were not up to the task of slicing and dicing such tough vegetation, and looked elsewhere for their preferred diet (Mallon and Anderson, 2014). Nodosaurs and some other megaherbivores had teeth better-suited to a tougher, more fibrous diet than ankylosaurs.


Though now almost a quarter of a century out-of-date, I love the comprehensive feel and endless line drawings in the Dinosaur Data Book (Lambert et al., 1998). This compact work comprises a major A-Z of dinosaur species, notes on dinosaur taxonomy, anatomy and paleoecology, and worldwide regional summaries of dinosaur distributions, lists of dinosaur collections in museums, and more. Worldwide "range maps" provide at-a-glance summaries of dinosaur finds. There are notes on dinosaurs of Mongolia and China (pp.246-249), compact profiles of nodosaurs and ankylosaurs (pp.167-168), and brief notes on many genera, including the late Jurassic- late Cretaceous nodosaurs such as Minmi and Struthiosaurus (pp.77, 96, 239) and mid- to late-Cretaceous ankylosaurs (e.g., Ankylosaurus and Tarchia, pp.42, 97).


Royal Ontario Museum, Toronto (December 2018), and museums in Asian capitals (2006-2019)

1. Toronto. Victoria Arbour and David Evans, in a beautifully illustrated 2018 book, explain the discovery, excavation, preparation, geological context and significance of a newly- found genus of ankylosaur from a quarry at Havre in northern Montana, just south of the Alberta border. The 2014 find occurred as a professional team was digging for a nearby tyrannosaur skeleton, and happened by chance on the tail of "Zuul". Following recovery of the remains, the dinosaur was prepared at Research Casting International in Trenton, Ontario. A popular article referred to RCI's unique 35-year expertise in sample preparation of large fossils (Hendry, 2019). The original block of stone containing the Zuul skeleton (complete except for the legs) weighed more than 35,000 pounds (15.89 tonnes). Zuul is said to be the most complete club-tailed dinosaur ever found in North America (Greshko, 2019).

Zuul was beautifully preserved. In a separate instance, the superb fossil preservation of the front half of a nodosaur, a form akin to an ankylosaur, a heavily armoured herbivorous dinosaur, was described by Greshko and Clark (2017). That discovery was made in March 2011 at the Millennium mine, one of the tar sands operations in northeast Alberta, located 27 km (17 miles) north of Fort McMurray. This fossil was dated by context at some 110 Ma.

There are larger and more famous institutions with dinosaur displays in Canada, but a fine place to visit is the small Hudson's Hope Historical Museum, with friendly staff and interesting exhibits. Hudson's Hope is a small town in the Peace River country of east-central British Columbia. The area has seen a number of dinosaur discoveries since 2000, including ornithopod remains and ankylosaur trackways (Hudson's Hope Museum, 2016).

Zuul became the star of a wonderful special exhibit at the Royal Ontario Museum. A visit on 17 December 2018 was a real treat. The host rocks of the remains are the late Cretaceous strata of the Judith River Formation, which represent a swampy forest habitat, like much of modern Louisiana or Florida.

Apparently, palaeontologists have identified over 50 kinds of ankylosaur, less than 5% of all known dinosaurs. They probably lived in small groups as juveniles, and then were more solitary. They had very small brains, but plenty of armour! Zuul crurivastator (76 Ma, 6 m long, 2.5 tonnes) was considerably larger than Crichtonsaurus, but smaller than the eponmymous genus, Ankylosaurus, which lived closer to the end-Cretaceous extinction event and was notably larger (68-66 Ma, 9-10 m long, 8 tonnes, found in western N.America). This was thus one of the last of its lineage. The R.O.M. collection also has a Mymoorapelta, or at least the cast of the original from Mesa county, Colorado: at 150 Ma this was one of the first ankylosaurs discovered to date, and so the family of armoured dinosaurs had a cumulative life span of some 85 million years, beside which Homo sapiens's 250,000 years or so is a mere flash in the pan.

2. Ulaan Baatar and Beijing. The dinosaurs in east Asia are well represented in the museums. The Natural History Museum in downtown Ulaanbaatar, the capital of Mongolia, opened in a small house in the city centre in 1924. In 1954 it was moved to a far more imposing building. The museum has - for starters - impressive samples of minerals, meteorites and birds, but the star attraction is the dinosaurs, amongst other animal and plant fossils. There is a huge skeleton of the carnosaur Tarbosaurus and a mind-boggling pair of arms, complete with 30-cm claws, of what must have been a gigantic unknown carnivore. Ankylosaurus is on display, as are dinosaur eggs (NHM Mongolia visit, 2006). In Beijing, dinosaurs are scattered amongst at least 4 or 5 national and university collections, but here we need mention just the one which is our focus today. From 2016 to 2019 I was lucky enough to pay numerous visits to the Yifu Museum, which occupies the top three floors of a modern building on the campus of the China University of Geosciences - Beijing (the index at foot of page has links to a number of other interesting exhibits at this excellent museum). The tenth floor houses the dinosaur display, inevitably a real attention-grabber. The displays include the three examples of Crichtonsaurus bohlini Dong, 2002, each roughly 4 metres long. Named for the Jurassic Park author Michael Crichton, this genus is an ankylosaur from the late Cretaceous of Liaoning, the southernmost province in the region of Manchuria, northeast China. The displays include a Zhejiangosaurus, (another 5-metre ankylosaur or nodosaur, to me resembling a larger version of the Crichtonsaurus), from the upper Cretaceous of Zhejiang province in coastal southeast China. The museum signs and displays are attractive: my students were tasked with taking photographs of a favourite specimen and its label, and writing a short essay on the subject.


Anon (2016) The Museum of China University of Geosciences. Yifu Museum, China University of Geosciences - Beijing, Haidian district, Beijing., 106pp. (in Ch. and in Engl.).

Arbour,VM and Currie,PJ (2015) Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs. Journal of Systematic Palaeontology 14 no.5.

Arbour,V and Evans,DC (2018) Zuul: Life of an Armoured Dinosaur. Royal Ontario Museum, Toronto, 94pp.

Carpenter,K (2004) Redescription of Ankylosaurus magniventris Brown 1908 (Ankylosauridae) from the upper Cretaceous of the western interior of North America. CJES 41, 961-986.

Coombs,WP (1995) Ankylosaurian tail clubs of middle Campanian to early Maastrichtian age from western North America, with description of a tiny club from Alberta and description of tail orientation and tail club function. CJES 32, 902-912.

Cumbaa,SL, Currie,PJ, Dodson,P and Mallon,JC (2021) Dale Alan Russell (1937-2019): voyageur of a vanished world. CJES 58, 731-740.

Dong Z.-M. (2002) A new armored dinosaur (Ankylosauria) from Beipiao Basin, Liaoning Province, northeastern China, Vertebrata PalAsiatica 40 no.4, 276-285

Graves,W (editor) (1993) North America in the Age of Dinosaurs. National Geographic 183 no.1, map supplement, January.

Greshko,M (2019) A new dino revealed. National Geographic 235 no.3, 28-30, March.

Greshko,M and Clark,R (2017) Turned to stone. National Geographic 231 no.6, 92-105, June.

Henderson,DM and Tanke,DH (2010) Estimating past and future dinosaur skeletal abundances in Dinosaur Provincial park, Alberta, Canada. CJES 47, 1291-1304.

Hendry,L (2019) More fossil finds for RCI. Community Press, Belleville, Ontario, 16-17, 31 January.

Hudson's Hope Museum (2016) Hudson's Hope Historical Museum. Hudson's Hope Historical Museum, 9510 Beattie Drive, P.O. Box 98, Hudson's Hope, B.C., museum visit, 08 August.

Lambert,D and the Diagram Group (1998) Dinosaur Data Book: Facts and Fictions about the World's Largest Creatures. Diagram Visual Information and Avon Books, New York, 1991, updated version published by Gramercy Books (Random House), New York, 320pp.

Liu,J, Ji,Q, Gao,Y and Li,Z (2011) A new species of the ankylosaurid dinosaur Crichtonsaurus (Ankylosauridae: Ankylosauria) from the Cretaceous of Liaoning Province, China. Acta Geologica Sinica 81 no.6, 883 - 897.

Mallon,JC and Anderson,JS (2014) The functional and palaeoecological implications of tooth morphology and wear for the megaherbivorous dinosaurs from the Dinosaur Park Formation (Upper Campanian) of Alberta, Canada. PlosOne, published 11 June,

Nath,TT, Yadagiri,P and Moitra,AK (2002) First record of armoured dinosaur from the lower Jurassic Kota Formation, Pranhita-Godavari valley, Andhra Pradesh. J.Geol.Soc.India 59, 575-577.

NHM Mongolia (2006) Natural History Museum of Mongolia. Natural History Museum of Mongolia, Sambuu Street, Khuvsgalchid Avenue, Chingeltei district, Ulaanbaatar, museum visit, 16 June.

Norman,D (1991) Dinosaur! Macmillan, New York, 1994 edition, 288pp.

Parsons,WL and Parsons,KM (2009) A new ankylosaur (Dinosauria: Ankylosauria) from the lower Cretaceous Cloverly Formation of central Montana. CJES 46, 721-738.

Penkalski,P and Blows,WT (2013) Scolosaurus cutleri (Ornithischia: Ankylosauria) from the upper Cretaceous Dinosaur Park Formation of Alberta, Canada. CJES 50, 171-182.

Sun,B-N, Du,B-X, Ferguson,DK, Chen,J-L, He,Y-L and Wang,Y-D (2013) Fossil Equisetum from the Lower Cretaceous in Jiuquan Basin, Gansu, Northwest China and its paleoclimatic significance. Palaeogeography, Palaeoclimatology, Palaeoecology 385, 202-212.

Vickaryous,MK, Russell,AP, Currie,PJ and Zhao,X-J (2001) A new ankylosaurid (Dinosauria: Ankylosauria) from the lower Cretaceous of China, with comments on ankylosaurian relationships. CJES 38, 1767-1780.

Yifu Museum (2016,2019) The Yifu Museum. on the campus of the China University of Geosciences, Xueyuan Road, Haidian district, north Beijing (numerous visits, including 23 March 2016 and 23 April 2019).

Graham Wilson, 11 October 2021, 05-06 December 2021, update 30 January 2022.

Read more about this interesting dinosaur family at Wikipedia,

Visit the "Rock of the Month" Archives,

or browse by category in the
"Rock of the Month Index"
(specimens related to China, and Beijing, appear below).
Provenance of specimens:
CAGS = China Academy of Geological Sciences, Beijing
CUGB = China University of Geosciences, Beijing (Grounds and Yifu Museum)
NGMC = National Geological Museum of China, Beijing
TGSL = Turnstone / Wilson collection
Various = Other private collections
YMY = Yuanmingyuan, Old Summer Palace, Beijing

Class/Group/Family 16 Topics across China --- 中国 (Zhong guo) --- such as samples in Beijing museums Site
The "Rock of the Month"
Tektite (glass) ---- #55 --- Tektites from Guangdong, China TGSL
Feldsparphyric ornamental "peony" stone --- #178 --- Porphyritic metabasite from Henan, China CUGB
Rapakivi granite (building stone) --- #179 --- Textures in a rapakivi granite, Beijing, China CUGB
Arsenic ore minerals --- #180 --- Arsenic sulphides, realgar and orpiment, from (?) Hunan, China CUGB
Superb crinoid fossils --- #181 --- Traumatocrinus, exceptional crinoid fossil from Guizhou, China NGMC
Beryl, beryllium cyclosilicate, gemstone --- #186 --- Prismatic beryl from (?) Yunnan, China CUGB
Vertebrate fossil, historically significant --- #201 --- Mesosaurus, fossil reptile & mascot for Gondwanaland (Brazil, via Guangxi, China) CUGB
Ornamental carving stone, China --- #203 --- Qingtian stone, superb lapidary material from Zhejiang, China CUGB
Ophiolitic chromitite --- #205 --- Chromitite, Luobusa ophiolite, southern Tibet (Xizang, China) CAGS
Nephrite jade --- #207 --- Massive jade as decorative piece, from China Various
Peridotite xenoliths in basalt --- #217 --- Mantle nodules and megacrysts, Hebei, China TGSL / CAGS
Tempestite dolostone of Jixian age --- #219 --- Tempestite with algal mats, Tianjin, China CUGB / YMY
Foraminifera from Java, Indonesia --- #226 --- Nummulite fossil Camerina CUGB
Orange barite on quartz --- #228 --- Barite, Xiefang mine, Jiangxi province, China TGSL
Vertebrate fossil --- #229 --- Keichousaurus hui, fossil reptile,China CUGB
Vertebrate fossil --- #248 --- Crichtonsaurus, ankylosaur, China - YOU ARE HERE! CUGB