Bone Cancer Rates in Dinosaurs Compared with Modern Vertebrates
Bone Cancer Rate in the Fossil Record
Bone Cancer Rates in Dinosaurs Compared with Modern Vertebrates 
L.C. Natarajan1, A.L. Melott1, B.M. Rothschild2, and L.D. Martin2 
1 Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045 
2 Biodiversity Research Center, University of Kansas, Lawrence, KS 66045 
ABSTRACT 
Data on the prevalence of bone cancer in dinosaurs is available from past radiological examination of 
preserved bones.  We statistically test this data for consistency with rates extrapolated from information on 
bone cancer in modern vertebrates, and find that there is no evidence of a different rate.  Thus, this test 
provides no support for a possible role of ionizing radiation in the K-T extinction event. 
INTRODUCTION 
Cancer is one of the few diseases that can be reliably diagnosed in vertebrate remains (Rothschild and 
Martin 2006). Cancer prevalence may potentially help shed light on biosphere stress.  Some scenarios for 
biodiversity fluctuation and mass extinctions include radiation effects, which might increase the cancer rate 
(e.g. Medvedev and Melott 2007).  Since dinosaurs were involved in a major mass extinction, it is 
interesting to see whether there is any evidence of an elevated cancer rate. 
While primary bone cancer can be defined as cancer that begins in the bone, secondary or metastatic bone 
cancer is cancer that originates elsewhere in the body and spreads to the bone. Bone is the third most 
common site for metastasis after lung and liver (Alvarez 1948; Abrams, Spiro and Goldstein 1950; 
Wierman, Clagett and McDonald 1954; Resnick 2002). Whereas a variety of cancers can spread to the 
bone, the most common forms in humans are breast, prostate, lung, kidney and thyroid (American Cancer 
Society 2007). In this study, the prevalence of secondary bone cancer in dinosaurs is examined for 
consistency with rates in modern vertebrates. 
While 2-3% benign hemangiomas (proliferation of vascular endothelium) were found in the family 
Hadrosauridae, only one case of metastatic cancer was found (within the same family). The diseased 
vertebra was that of an Edmontosaurus (Rothschild et al. 2003) specimen from the Maastrichtian stage. It is 
particularly interesting that this case came from near the end-Cretaceous, when the extinction event took 
place. We note that the elevated rate of hemangiomas was also Maastrichtian, which is interesting, but we 
have not studied this question since it cannot be excluded that, for example, it is a consequence of the diet 
or some other peculiarity of this family.  The focus of our study is to do a statistical test for consistency 
between the rates in dinosaurs versus modern vertebrates. 
DATA AND METHODS 
In order to test for consistency, we need to establish an expected rate based on data from modern 
vertebrates, and then ask whether the event in the dinosaur fossil record is consistent with that rate. 
While the spine is the most commonly affected area of bone metastasis in the human skeleton, the next 
most common areas of spread include the ilium, pubis, ischium, proximal femur, femora and skull 
(American Cancer Society 2007). Thus, if a more comprehensive study is to be performed, examination of 
these regions is suggested. Furthermore, as suggested by Rothschild and Rothschild (1995), visual 
examination is complementary to radiologic examination and therefore should be included if the 
epidemiology of metastatic disease is to be determined reliably.  However, the radiologic method alone was 
the basis of the sample and control rate estimates used in this study. 
The prevalence of bone cancer in human skeletons was examined.  We justify the comparison based on a 
superficial similarity of large vertebrates with substantial life spans (Erickson et al. 2006). The rate of bone 
metastasis was estimated with respect to x-ray identified metastatic disease in the Hamann-Todd Collection 
(Rothschild and Rothschild 1995).  
The Hamann-Todd Collection is the largest and best preserved compilation of human skeletons for which a 
background demographic is known (Rothschild and Woods 1991; Rothschild and Martin 1993). From a 
total of 2906 defleshed skeletons, 33 cases of metastatic disease were identified fluoroscopically, yielding a 
probability of 1.14 %. Based on necropsy results of captive wild animals (Effron, Griner and Benirschke 
1977), the rate of cancer in reptiles is approximately 1/8th that found in humans. Thus, the rate of cancer in 
dinosaurs can be tested for consistency with a rate of 0.142%.  
Another estimate can be made based on the rate in birds. The rate of macroscopically observable cancer in 
birds was less than 24 in 50,000 (Rothschild and Panza 2005), indicating that the rate of cancer in dinosaurs 
can be tested for consistency with 0.048%. The Poisson distribution was subsequently applied to both rates 
in order to calculate probability.  Our null hypothesis is that the rate of such cancer in dinosaurs is not 
higher than either of these rates. 
The data concerning the prevalence of cancer in the fossil record was presented in Rothschild et al. (2003).  
The epidemiology of tumors in dinosaurs was investigated by fluoroscopically screening dinosaur 
vertebrae, a technique which allowed the examination of vertebrae in real time, thus negating the need for 
film.  A total of 10,312 vertebrae from 708 individual dinosaurs of varying families were examined, and 
one such tumor was found. 
RESULTS 
The malignant Edmontosaurus tumor reported by Rothschild et al. (2003) is metastatic cancer of unknown 
(primary) origin. In the table below, we show the probability of finding various numbers of subjects with 
tumors (left column) in a sample of 708 examined, assuming the rate for reptiles (center column) and birds 
(right column) It was determined that the rate of metastatic bone disease in the dinosaur fossil record is in 
fact consistent with the predicted rate of bone metastasis in the dinosaur record (Table 1). The probability 
of finding less than one cancer is 37% according to the reptilian cancer rate, and 71% according to the 
avian rate, so the observed event does not represent an elevated rate. We cannot negate the null hypothesis. 
Thus, there does not appear to be an elevated rate of bone cancer in the dinosaur fossil record.  Note that if 
the null hypothesis had been formulated as “not lower rate”, we would not be able to reject that either, 
based on the size of the sample and the expected rates. 
Dinosaurs (708) Reptiles Birds 
# with cancer Probability Probability 
0 0.36605 0.71188 
1 0.36787 0.24193 
2 0.18486 0.04111 
3 0.06193 0.00466 
4 0.01556 0.00040 
5 0.00313 0.00003 
6 0.00052 0.00000 
7 0.00008 0.00000 
8 0.00001 0.00000 
Table 1 Examination of vertebrae from 708 dinosaurs  
revealed 1 case of metastatic disease. Thus, the 
frequency of metastatic bone cancer is consistent with  
the risk estimated from rates in modern vertebrates, as  
determined using the Poisson distribution. 
DISCUSSION 
We have asked whether the bone cancer rate in dinosaurs is consistent with rates for modern vertebrates.  
Results of past examination of dinosaur fossil bones for evidence of metastatic bone cancer are tested for 
consistency with available information on rates in modern vertebrates.  We were able to make two rate 
estimates, not more than a factor of three apart, based on available data.  We then ask about the probability 
of finding one bone cancer in 708 dinosaurs based on these assumed rates.  We find that with either rate, 
this is not an unexpected outcome.  We conclude that there is no evidence for an abnormal rate of bone 
cancer in dinosaurs. 
Exposure to ionizing radiation can elevate the rate of bone cancers (Brenner et al. 2003).  A variety of 
astrophysical sources of such radiation have been hypothesized to have a role in extinction events (e.g. 
Fields 2004; Medvedev and Melott 2007).  It is therefore interesting to ask whether there is evidence for an 
elevated cancer rate as a possible signal for a role in ionizing radiation. The answer is no. There is however, 
a residual question of a somewhat elevated rate of benign hemangiomas in the family Hadrosauridae which 
is outside the scope of this study, but may deserve further consideration in the future.   
ACKNOWLEDGEMENTS 
This research was supported by NASA Astrobiology: Exobiology and Evolutionary Biology grant 
NNG04GM14G, the University of Kansas Honors Program, and by the KU Student Senate. 
LITERATURE CITED 
Abrams, H.L., Spiro, R., Goldstein, N. 1950. Metastases in carcinomas: Analysis of 1000 autopsied 
cases. Cancer 3 p. 74-85. 
Alvarez, G.H. 1948. Clinica del cancer de pulmon. Revista de la Asociacion Medica Argentina 62 p. 
690-694. 
American Cancer Society. Cancer Reference Information. Detailed Guide: Bone Metastasis.. URL 
[http://www.cancer.org/docroot/CRI/content/ 
CRI_2_4_1X_What_Is_bone_metastasis_66.asp]. Date accessed [April 2007]. 
Brenner, D.J., Doll R., Goodhead, D.T., Hall, E.J., Land, C.E., Little, J.B., Lubin, J.H., Preston, D.L.,  
Preston, R.J., Puskin, J.S., Ron, E., Sachs, R.K., Samet, J.M., Setlow, R.B., Zaider, M. 2003. Cancer 
risks attributable to low doses of ionizing radiation: Assessing what we really know. Proceedings of 
the National Academy of Sciences 100 p 13761-13766. 10.1073/pnas.2235592100 
Effron, M., Griner, L., Benirschke, K. 1977. Nature and rate of neoplasia in captive wild mammals, 
birds and reptiles at necropsy. Journal of the National Cancer Institute, 59 p. 185-198. 
Erickson, G.M., Currie, P.J., Inouye, B.D., Winn, A.A. 2006. Tyrannosaur life tables: An example of 
nonavian dinosaur population biology. Science, 313 p. 213-217.  
Fields, B.D. 2004. Live radioisotopes as signatures of nearby supernovae. New Astronomy Reviews 48 
p 119-123. 
Medvedev, M. V., and Melott, A.L. 2007. Do extragalactic cosmic rays induce cycles in fossil 
diversity? Astrophysical Journal 664 p 879–889.   
Resnick, D.  2002.  Radiology of Bone and Joint Disease.   Saunders, Philadelphia. 
Rothschild, B.M., Martin, L. 1993. Paleopathology: Disease in the fossil record. CRC Press, London. 
Rothschild, B.M., Martin, L.D.  2006.  Skeletal Impact of Disease.  Museum of Natural History Press, 
Albuquerque, New Mexico. 
      Rothschild, B.M., Panza, R.K. 2005.  Epidemiologic assessment of trauma Independent    
      skeletal pathology in non-passerine birds from museum collections. Avian Pathology, 34 p.  
      212-219. 
Rothschild, B.M., Rothschild, C. 1995. Comparison of radiologic and gross examination for detection 
of cancer in defleshed skeletons. American Journal of Physical Anthropology, 96 p. 357-363. 
Rothschild, B.M., Tanke D.H., Helbling M., Martin L.D. 2003. Epidemiologic study of tumors in 
dinosaurs. Naturwissenschaften 90 p. 495-500. 
Rothschild, B.M., Woods, R.J. 1991. Spondyloarthropathy: Erosive arthritis in representative defleshed 
bones. American Journal of Physical Anthropology, 85 p. 125-134. 
Wierman, W.H., Clagett, O.T., McDonald, J.R. 1954. Articular manifestations in pulmonary diseases. 
An analysis of their occurrence in 1024 cases in which pulmonary resection was performed. Journal of 
the American Medical Association, 155 p. 1459-1463.
