Debunking Steve Culbreth’s “California Dinosaurs”

IMG_7041-a1van0lvm9.png A map of the Purisima Formation in California. Image from Boessenecker et al. (2014).


Steve Culbreth was a former member of Dinosaur Home known for his unorthodox and controversial ideas regarding paleontology. He claimed to be finding dinosaur fossils in Half Moon Bay, California (an area where dinosaur remains are unknown), including numerous bones and even preserved soft tissue. While others have criticized his hypotheses, this is the first attempt at a thorough analysis and rebuttal. This blog post is mainly a response to Culbreth’s post “Forensic Paleo Biology: A Case for Mesozoic Habitation of Dinosaurs in California” from 2015. Here Culbreth’s hypothetical model of dinosaur habitation of California during the Late Cretaceous and the evidence he provides for it are refuted.

Geological and Biostratigraphical Issues


Figure 1: Age of the Purisima Formation

When analyzing Culbreth’s claims it is important to first consider the geology of Half Moon Bay. Culbreth asserts that the sediments exposed along the shores of Half Moon Bay are 88 million years old, dating to the Coniacian stage of the Late Cretaceous. He does not elaborate on how this date was reached and neglects to name the geologic formation in question. In reality the exposures along the Pacific coast at Half Moon Bay are not Cretaceous, nor even Mesozoic. They are instead comprised of the Purisima Formation (Powell 1998), which radiometric dating indicates is late Miocene to early Pliocene in age, between 7 and 2.6 million years old (Powell et al. 2007). Instead of the estuarine/deltaic deposition that Culbreth proposes, the Purisima is entirely marine in origin and was formed at the bottom of a shallow sea (Boessenecker et al. 2014).


Comparison of Culbreth’s fossil, cf. Anadara trilineata, with the modern species Anadara brasiliana. Images from Culbreth (2015) and Wikimedia Commons.

The only evidence Culbreth attempts to provide for a Late Cretaceous date is his fossil of what he calls a “beefheart cockle”, which he states went extinct at the end of the Cretaceous. This is actually a fossil of the ark clam Anadara, a genus that ranges from the Cretaceous to the present day. A. trilineata is known from the Purisima Formation (Moore 1983, Powell et al. 2007) and Culbreth’s fossil is likely referable to this species. Culbreth’s use of Anadara as an index fossil is flawed and in no way indicates that the strata are Cretaceous in age.

Paleobiogeographical Issues


Figure 2: Temporal Inconsistencies in Culbreth’s Model

Even disregarding the dubious nature of Culbreth’s evidence, his hypothetical model for the dinosaur habitation of California is not internally consistent. The date that he proposes (88 Ma) and the types of dinosaurs he claims to have found (T. rex, titanosaurs) are contradictory. For example, the temporal range of T. rex is restricted to the late Maastrichtian, between 69 and 66 Ma. The Tyrannosauridae as a whole doesn’t emerge until the Campanian (Loewen et al. 2013). Additionally, there was a hiatus of sauropods in North America that occurred from the Cenomanian-Turonian boundary (93.9 Ma) until either the late Campanian (c. 76 Ma) or the Campanian-Maastrichtian boundary (72.1 Ma) (Mannion & Upchurch 2011). During the Coniacian, neither tyrannosaurs nor titanosaurs would have been present in North America, let alone California. Culbreth’s model demonstrates little knowledge of the paleobiogeography of North America during the Late Cretaceous.

Dubious Fossils

Culbreth bases his whole hypothesis on fossils that he has collected and identified as the remains of dinosaurs. Unfortunately for the credibility of his hypothesis, these are all misidentifications.


Comparison of Culbreth’s first “titanosaur vertebra” with the caudal vertebrae of Cetotherium riabinini. Images from Culbreth (2015) and Gol’din et al. (2014).

First and foremost are the specimens which Culbreth purports to be titanosaur vertebrae. The first he claims is a “highly identifiable caudal”, which is ironic considering its heavily-worn state. This type of abrasion is common in fossils found in marine sediments, including the Purisima Formation (Boessenecker et al. 2014). Above I have compared it with the distal caudals of the cetotheriid whale Cetotherium riabini from the late Miocene of Ukraine (Gol’din et al. 2014). Cetotheriid whales like Herpetocetus are known from the Purisima (Powell et al. 2007), so it is possible that this fossil represents a cetotheriid caudal. However, its poor preservation makes a certain identification difficult.

Comparison-3-y20px2huep.pngComparison of Culbreth’s second “titanosaur vertebra” with a lumbar vertebra (D) from Cetotherium riabinini. Images from Culbreth (2015) and Gol’din et al. (2014).

The second “titanosaur vertebra”, which Culbreth identifies as a “dorsal”, is better-preserved than the first. Again I have above compared it with Cetotherium riabinini, this time with a lumbar vertebra (Gol’din et al. 2014). It appears Culbreth’s specimen has the transverse processes and neural spine worn-off, which occurs in vertebrae from marine depositional environments like the Purisima (Boessenecker et al. 2014). This vertebra is most likely a lumbar from a cetotheriid whale, and may have even come from the same individual as the first.

Comparison-4-863duhyuft.pngComparison of Culbreth’s “T. rex coprolite” with a phosphate nodule from the Purisima Formation. Images from Culbreth (2015) and The Fossil Forum.

Next is Culbreth’s “T. rex coprolite”, which is actually a pseudofossil. The Purisima Formation is rich in phosphate, as many marine formations are, with phosphate nodules being abundant. These nodules are dark brown to black in color, and can form conglomerate or larger concretions (Boessenecker et al. 2014). This “coprolite” is quite clearly a piece of phosphatic conglomerate.

Comparison-5-u16oznu4e4.pngComparison of Culbreth’s “titanosaur footprint” with a generalized titanosaur trackway. Images from Culbreth (2015) and Wilson & Carrano (1999).

Last is Culbreth’s “titanosaur footprint”, which is the most dubious of all the evidence he presents. The low quality of the photograph makes it difficult to tell if it is just natural weathering in rock or if it is an imprint in mud. It does not match the shapes of either the manus or pes prints of titanosaurs (Wilson & Carrano 1999). Also note that when dinosaur footprints are preserved they are found in trackways, not just single footprints. Nothing about this indicates a footprint of any kind and it seems to be a case of pareidolia.

Legitimate California Dinosaurs

Non-Avialan-Dinosaurs-from-California-205cwg4ucg.pngTable 1: Non-Avialan Dinosaurs from California

The currently known dinosaurs from California are the basal ankylosaurid Aletopelta (Ford & Kirkland 2001), the saurolophin hadrosaurid Augustynolophus (Prieto-Márquez et al. 2014), and an indeterminate ornithopod (Hilton et al. 1997). Dinosaurs are rare in California, as well as the whole Pacific coast, for two reasons. The first is the relative scarcity of Mesozoic strata in the region, and the second is that most of the present Mesozoic formations are marine in origin (Peecook & Sidor 2015). All of the Californian dinosaur material comes from marine/coastal sediments; it is likely that they were “bloat and float” carcasses that washed out to sea, which are rarely preserved. Considering this makes it all the more improbable that a Late Cretaceous bonebed of dinosaur fossils exists in Half Moon Bay.


In short, Culbreth’s hypothesis do not stand up to scrutiny and can be thoroughly debunked. Whether his claims are blatant lies or the result of a lack of research, I do not know, but they are demonstrably false. His evidence is based on simple misidentifications, and his hypothesis contradicts what is known about geology, stratigraphy, paleobiogeography, etc. This post should serve as a word of caution to not take extraordinary and improbable hypotheses at face-value, and to investigate and research unsourced claims carefully. Dispelling pseudoscience like this contributes to legitimate scientific discussion and progress.


So... what do you think? Please leave me a comment.


  • JMD: Good read. On the home page, I misread the first 3 words as "Incorrect Steve Culbreth" as if you gave him a negative nickname. xD
  • rockhead: Sorry I made an **** out-of you Kaman, But then again your nothing but an avatar. So, by me being banned you can say what you want and with J Md you can regain your conventional, Old fashion Geo-paleo knowledge that can never be revised while you domenate this site for your own selfish pleasure.
    I came to this site to enable everyone to discover, on a daily basis what I have found to be invisible to most everyone, because of the prevailing conventional conjecture that they live-by.
  • JMD: Are you dinodragonasauraus?
  • Vale: Thank you Carnoferox for taking the time to explain why some of his theories were incorrect rather than just make rude comments. I hope that others will follow your example and take the time to illustrate why something is incorrect rather than just make fun of the person. This way, we all can learn something :)
  • Carnoferox: It is always good to demonstrate with evidence why someone is wrong rather than resorting to ad hominem attacks.
  • tzavecz: Very nicely done and its nice to see the references.
    It’s a shame Steve didn’t really follow up on his collection. In spite of his ’soft tissue’ theories, he had a collection of fossils that is still significant and could have been very fulfilling to learn about them and the period of their lives.
  • Carnoferox: It is a shame considering the Purisima Formation has an interesting variety of Mio-Pliocene marine fossils, including mollusks, fish, cetaceans, and even walruses.

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