NEW INFORMATION ABOUT TWO FAMOUS DINOSAURS

NEW INFORMATION ABOUT TWO FAMOUS DINOSAURS

The dinosaurs Tyrannosaurus and Triceratops are arguably the most popularly known dinosaurs. Some latest research has proposed new viewpoints about these two dinosaurs, and the purpose of this blog post is to bring this new information to your attention. 

                                  TYRANNOSAURIS REX

This apex meat-eating dinosaur lived in western North America during the Late Cretaceous (69 to 66 million years ago), stood 15 feet high, reached lengths of over 40 feet, and weighed up to 8 tons (Wikipedia, 2025). Since it was first recognized and described by Henry Fairfield Osborn in 1902, this dinosaur has been known as a single species. A recent study (Paul et al, 2022) proposed, however, that there were three species of A rebuttal study (Carr et al, 2022) supports, however, the previous conclusion that there was only a single species and that is T. rex. 

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                                           TRICERATOPS

This plant-eating dinosaur also lived in western North America (e.g., Montana and vicinity) during the Late Cretaceous (68 and 65) million years ago, was up to 20 to 30 feet long, and weighed up to 10 metric tons (Wikipedia, 2025). Since Triceratops was first discovered and described by Othniel Charles Marsh in 1887, there have been 16 (some say 17) species proposed for this plant-eating genus. Ostrom and Wellnhofer (1986) reported however that there was only a single species. More recently, Forster (1996) demonstrated that there were likely only two species: Triceratops horridus and its evolutionary successor, Triceratops prorsus. The subsequent trend these days is that most vertebrate paleontologists have similarly agreed that there were only two species (see Wikipedia, 2025).

REFERENCES

Carr, T. D. and six other authors. 2022. Insufficient evidence for multiple species of Tyrannosaurus in the latest Cretaceous of North America, etc. Evolutionary Biology 49(4):327-341. [pdf free and readily available].

Forster, C. A. 1996. Species resolution in Triceratops: cladistics and morphometric approaches. Journal of Vertebrate Paleontology 16 (2):259–270.

 

Ostrom, J.H. and P. Wellnhofer. 1986. The Munich specimen of Triceratops with a revision of the genus. Zitteliana 14:111–158.

Paul, G.S., W. Scott Persons IV, and J. Van Raalte. 2022. The tyrant lizard king, queen and emperor: multiple lines of morphological and stratigraphic evidence support subtle evolution and probable speciation within the North America genus Tyrannosaurus. Evolutionary Biology, 49:156-179.

GEOLOGY OF THE COCONINO PLATEAU, NORTHERN ARIZONA

Many people have either driven or taken the public train on the eastern edge of the Coconino Plateau, but very few people venture onto or across this very flattish terrain immediately south of the Grand Canyon.

In 1973, along with another geologist Michael J. Abrams, we spent nearly a year field mapping this plateau. We used a sturdy truck (via the Jet Prolusion Lab) to get around because the roads there are all rough dirt roads that typically could be difficult to navigate. We camped out for two weeks at a time, and then retreated, for a week,  to civilization. Mike drove back to Pasadena, California and I drove to Albuquerque. Via our field work, we created a geologic map of the Coconino Plateau, whose northern boundary is the edge of the Grand Canyon. The southern edge is many miles away. In between is an area home to a few cattle ranches. This plateau has only sparse vegetation (i.e., very few trees!).

We mapped the geology of the area by using standard geologic field procedures (i.e., feet on the ground and a map board in hand). In doing so, we followed the famous geologic dictum, which is “go and see.” We acquired “ground truth” of an area (as big as some states) that had never been geologically mapped in any kind detail. In addition to using the standard “air photos,” we had high-altitude photos taken by means of satellite[ ERTS = Earth Resources Technology Satellite] imagery. It took nine months of field work, and after we completed our traditional-style of mapping, we compared our geologic map with what could be discerned via satellite photography. These latter photos were enhanced by highly skilled computer-program specialists at the Jet Prolusion Laboratory in Pasadena, California. No one had every done such a detailed comparison before. Of course, nothing beats actually “ground truth” collected by field geologists, but some of the computer-enhanced images did reveal better evidence of features that we could not readily detect via standard geologic mapping (for example: poorly exposed faults and some potential ground-water zones).

Reference: 

Goetz, A.F.H. and seven other authors (including R.L. Squires and Mike Abrams). May 15, 1975. 188 pp. Technical Report 32-1597. Application of ERTS Images and image processing to regional geologic problems and geologic mapping in northern Arizona. 

This entire document can be viewed, for free, online at ntrs.nasa.gov

Figure 1. Overview of the Coconino Plateau, northern Arizona. The area at the top of this image is the Grand Canyon.

Figure 2. Ground view of a portion of the Coconino Plateau (1973).

Figure 3. Field vehicle loaned to us by the Jet Prolusion Lab (1973).

Figure 4. Geologic map of Squires and Abrams (published in 1975, see above).

Figure 5. Stratigraphic column of the rock layers exposed in the area mapped by Squires and Abrams (see Fig. 4 above). The colors (e.g., blue, green, orange, red, etc.) on that geologic map in Fig. 4 correspond to their respective stratigraphic unit (e.g., red = basalt flows), shown in the explanation (= the vertical row of the small boxes on the right side of Fig. 5).

TWO VERY RARE FOSSILS FROM SOUTHERN CALIFORNIA

FOSSIL 1:

Many years ago, Greg Slack, one of my colleagues, graciously gave me a rare specimen of an Upper Cretaceous, Turonian Stage, crinoid fossil “stem” that he found. This fossil is from siltstone in the Holz-Baker gradational transition zone of the Ladd Formation in the Santa Ana Mountains of Orange County, southern California. These sediments were deposited in shallow to moderately deep depths, during warm-water times.

As far as I know, this is the first crinoid fossil from this locale. Even though the specimen is missing its calyx (“head”), I was able to identify its “stem” as belonging to genus Neocrinus, a “relict” genus belonging either to family Balanocrinidae or Isocrinidae [depending on the researcher]. Both families have a geologic time range of about 23 million years ago [= earliest Miocene] to Recent.

Genus Neocrinus lives today in moderately shallow to relatively deep water [as deep as 1219 m] (from Florida, Grenada, Bahamas, and Cuba). A modern specimen of a Neocrinus blakei stem is shown below for comparison.

Classification

Kingdom Animalia

Phylum Echinodermata

Class Crinoidea

Family Balanocrinidae [or Isocrindae] 

Genus Neocrinus

Figure 1. A Late Cretaceous (Turonian Stage) Neocrinus sp. stem (7.8 cm length, 4 cm diameter) from the Ladd Formation in the Santa Ana Mountains of Orange County, southern California. This fossil is shown [alongside] a Recent specimen of Neocrinus blakei [= bright white color, calyx missing, length 8 cm, diameter 3 mm]. This Recent specimen is from 402-411 m depth, in the Old Bahama Channel of Punta Alegre, Cuba. Collector: unknown]. 

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FOSSIL 2:

After years of extensive collecting (see Squires, 1984), only a single specimen of a myliobatid shark-tooth plate has been found in the middle Eocene Llajas Formation of southern California (Squires, 1984). It was collected by, David Advocate, one of my Master’s Degree student, who graciously donated the specimen, which is figured for the first time herein.

Family Myliobatidae

   Aetobatus? sp.---this genus is characterized by having  narrow teeth

Figured below is a tooth plate called “pavement teeth,” which are used to crush crustaceans and clams living in shallow sandy ocean waters. This genus is characterized by having a toothplate comprised of narrow teeth.

Figure 2. Aetobatus? sp. (each division of the "ruler" is 1 cm); therefore the toothplate is 50 mm in length.

References

De Anda, M.V. 2011. Taxonomia y biogeografia de los crinoideos (Echinodermata: Crinoidea) de Mexico. [Tesis] Thesis, 181 pp. [Available online, for free].

Ebersole, J.A., D. Cicimurri, and G. L. Stringer. 2019. Taxonomy and biostratigraphy of the elasmobranch and bony fishes (Chondrichthyes and Osteichtyes) of the lower-to-middle Eocene (Ypresian to Bartonian) Group in Alabama, USA, including Claiborne and analysis of otoliths. European Journal of Taxonomy 585, pp. 1-274.

Squires, R.L. 1984. Megapaleontology of the Eocene Llajas Formation, Simi Valley, California. Contributions in Science No. 350, 76 pp.