Research Program & Publications
PDFs are available upon request. Google Scholar page is here. ORCID: 0000-0002-4261-1323
(a full publication list can be found further down this page)
(a full publication list can be found further down this page)
From Organisms to Ecosystems: integrative approaches to biodiversity research in deep-time
My research uses a systems approach to disentangle complex interactions between ecosystems, environments, and evolution in deep time.
My research uses a systems approach to disentangle complex interactions between ecosystems, environments, and evolution in deep time.
I) High-resolution palaeocommunity & palaeoenvironmental dynamics across time and space
A major component of the research in my lab focuses on analyzing trends in vertebrate community structure to test the responses of species and ecosystems to climate perturbations and other environmental conditions. In particular, I'm interested in understanding these patterns in the ancient 'non-analogue' ecosystems of the Cretaceous, as this period in Earth history records greenhouse climate conditions that are similar to some of the projected outcomes for climate change occurring on Earth today. Characterizing how species, ecosystems, and landscapes respond under such conditions may give us important insights about both the underlying differences of greenhouse vs. icehouse environments, as well as providing clues about potential differences in response beyond what we might predict based on our present-day knowledge alone (potentially aiding future conservation plans).
A major component of this research thus far has focused on the 3 million year span of the Belly River Group of Alberta, which records multiple major regional environmental and sea level changes, and uses a dataset of over 60 taphonomically-equivalent sites representing over 100,000 fossil specimens. Ongoing work on these strata involves additional site sampling, taxonomic revisions for more effective palaeocommunity analyses, the integration of functional trait metrics to assess differences in functional diversity vs. biodiversity, and the analysis of a suite of terrestrial palaeoclimate proxies to better understand the fine-scale environmental conditions (and changes) in these systems over time and across landscapes.
Most relevant studies (in addition to in-progress research):
Cullen, TM. and Nanglu, K (2024). Functional diversity and structure of Cretaceous coastal plain ecosystems. Conference Abstract, 2024 North American Paleontology Conference. Ann Arbor, Michigan. June 2024.
Thompson, MGW., Cullen, TM., Evans, DC., Schröder-Adams, C., Ryan, MJ. (2024). Multi-proxy paleoenvironmental and paleoecological reconstruction of the Foremost Formation (Upper Cretaceous, Campanian) of Alberta. Palaios 39(12): 425-443. doi: 10.2110/palo.2022.061
Cullen, TM. and Evans, DC. (2016). Palaeoenvironmental drivers of vertebrate community composition in the Belly River Group (Campanian) of Alberta, Canada, with implications for dinosaur biogeography. BMC Ecology. doi: 10.1186/s12898-016-0106-8
Cullen, TM., Fanti, F., Capobianco, C., Ryan, MJ., and Evans, DC. (2016). A vertebrate microsite from a marine-terrestrial transition in the Foremost Formation (Campanian) of Alberta, Canada, and the use of faunal assemblage data as a palaeoenvironmental indicator. Palaeogeography, Palaeoclimatology, Palaeoecology 444: 101-114. doi:10.1016/j.palaeo.2015.12.015
A major component of this research thus far has focused on the 3 million year span of the Belly River Group of Alberta, which records multiple major regional environmental and sea level changes, and uses a dataset of over 60 taphonomically-equivalent sites representing over 100,000 fossil specimens. Ongoing work on these strata involves additional site sampling, taxonomic revisions for more effective palaeocommunity analyses, the integration of functional trait metrics to assess differences in functional diversity vs. biodiversity, and the analysis of a suite of terrestrial palaeoclimate proxies to better understand the fine-scale environmental conditions (and changes) in these systems over time and across landscapes.
Most relevant studies (in addition to in-progress research):
Cullen, TM. and Nanglu, K (2024). Functional diversity and structure of Cretaceous coastal plain ecosystems. Conference Abstract, 2024 North American Paleontology Conference. Ann Arbor, Michigan. June 2024.
Thompson, MGW., Cullen, TM., Evans, DC., Schröder-Adams, C., Ryan, MJ. (2024). Multi-proxy paleoenvironmental and paleoecological reconstruction of the Foremost Formation (Upper Cretaceous, Campanian) of Alberta. Palaios 39(12): 425-443. doi: 10.2110/palo.2022.061
Cullen, TM. and Evans, DC. (2016). Palaeoenvironmental drivers of vertebrate community composition in the Belly River Group (Campanian) of Alberta, Canada, with implications for dinosaur biogeography. BMC Ecology. doi: 10.1186/s12898-016-0106-8
Cullen, TM., Fanti, F., Capobianco, C., Ryan, MJ., and Evans, DC. (2016). A vertebrate microsite from a marine-terrestrial transition in the Foremost Formation (Campanian) of Alberta, Canada, and the use of faunal assemblage data as a palaeoenvironmental indicator. Palaeogeography, Palaeoclimatology, Palaeoecology 444: 101-114. doi:10.1016/j.palaeo.2015.12.015
II) Isotope approaches to characterize environmental & ecological interactions in ancient systems
Another primary focus of research in my lab involves applying isotopic and elemental analyses to reconstruct diet, environmental conditions, trophic interactions, and habitat preferences in extant and ancient systems. One of the conventional issues in using fossil data is that there are many aspects of the biology which do not fossilize (e.g. behaviour, specifics of diet, variations in movement patterns through life, etc.), but which we are still interested in understanding. Geochemical proxies are useful in this regard as they involve the measurement of particular naturally occurring isotopes or the ratios of certain trace elements (often metals) which have been ingested by an animal during its life and incorporated into its soft and hard tissues (particularly the tooth enamel and bones, both of which do readily fossilize). In this way, animals 'are what they eat', and a record of their diet, behaviour, and movements can all be recorded permanently in their fossilized remains for us to measure many millions of years later.
A major focus so far has been on Late Cretaceous coastal floodplain ecosystems and their modern near-analogue environments, providing a finer-resolution complement to the ecosystem-scale / macroecological approach listed in section [I] above. The goals of this research are two-fold: 1) to understand the community structure and food webs of the Late Cretaceous, and their relation to various environmental parameters, given that there are a number of unusual biogeographic and ecological patterns documented via fossil occurrence data which suggest differences in baseline ecosystem function in these greenhouse environmental systems compared to large vertebrate communities today; and 2) to use the Cretaceous as as a baseline model both for understanding ecological processes in non-analog greenhouse systems and apply those insights to form predictions of future ecological shifts as the Earth transitions from icehouse to greenhouse conditions as a result of ongoing climate change (again, in concert with similar goals for analyses in section [I]).
Most relevant papers (in addition to in-progress research):
Cullen, TM., Cousens, B. (2024). New geochemical insights in Mesozoic terrestrial paleoecology and evidence for omnivory in troodontid dinosaurs. GSA Bulletin. doi: https://doi.org/10.1130/B37077.1
Cullen, TM., Longstaffe, FJ., Wortmann, UG., Huang, L., Evans, DC. (2023). Anomalous 13C-enrichment in Mesozoic vertebrate enamel reflects environmental conditions in a ‘vanished world’ and not a unique dietary physiology. Paleobiology: 1-15. doi: 10.1017/pab.2022.43
Cullen, TM., Zhang, S., Spencer, J., Cousens, B. (2022). Sr-C-O isotope signatures reveal herbivore niche-partitioning in a Cretaceous ecosystem. Palaeontology. doi: https://doi.org/10.1111/pala/12591
Cullen, TM., Longstaffe, FJ., Wortmann, UG., Huang, L., Fanti, F., Goodwin, MB., Ryan, MJ., Evans, DC. (2020). Large-scale stable isotope characterization of a Late Cretaceous dinosaur-dominated ecosystem. Geology 48(6): 546-551.
A major focus so far has been on Late Cretaceous coastal floodplain ecosystems and their modern near-analogue environments, providing a finer-resolution complement to the ecosystem-scale / macroecological approach listed in section [I] above. The goals of this research are two-fold: 1) to understand the community structure and food webs of the Late Cretaceous, and their relation to various environmental parameters, given that there are a number of unusual biogeographic and ecological patterns documented via fossil occurrence data which suggest differences in baseline ecosystem function in these greenhouse environmental systems compared to large vertebrate communities today; and 2) to use the Cretaceous as as a baseline model both for understanding ecological processes in non-analog greenhouse systems and apply those insights to form predictions of future ecological shifts as the Earth transitions from icehouse to greenhouse conditions as a result of ongoing climate change (again, in concert with similar goals for analyses in section [I]).
Most relevant papers (in addition to in-progress research):
Cullen, TM., Cousens, B. (2024). New geochemical insights in Mesozoic terrestrial paleoecology and evidence for omnivory in troodontid dinosaurs. GSA Bulletin. doi: https://doi.org/10.1130/B37077.1
Cullen, TM., Longstaffe, FJ., Wortmann, UG., Huang, L., Evans, DC. (2023). Anomalous 13C-enrichment in Mesozoic vertebrate enamel reflects environmental conditions in a ‘vanished world’ and not a unique dietary physiology. Paleobiology: 1-15. doi: 10.1017/pab.2022.43
Cullen, TM., Zhang, S., Spencer, J., Cousens, B. (2022). Sr-C-O isotope signatures reveal herbivore niche-partitioning in a Cretaceous ecosystem. Palaeontology. doi: https://doi.org/10.1111/pala/12591
Cullen, TM., Longstaffe, FJ., Wortmann, UG., Huang, L., Fanti, F., Goodwin, MB., Ryan, MJ., Evans, DC. (2020). Large-scale stable isotope characterization of a Late Cretaceous dinosaur-dominated ecosystem. Geology 48(6): 546-551.
III) Osteohistology to study growth variability, body-size evolution, and autecology
Another major component of research in my lab is the use of bone cross-sections to study age and growth in vertebrates. Similar to the purpose of applying isotope approaches, I examine bone cross-sections as a way to learn about growth in extinct (and extant animals), where we are not able to simply observe an animal growing in-life and taking ongoing measurements of its weight and dimensions (as one might do for a zoo animal, for example). By using these approaches we can gain similar amount of information for animals which have been extinct for tens of millions of years.
This research involves quantifying the variability present in multiple growth proxies (e.g. tissue organization, presence of annual growth marks, etc) found in bone microstructure and reconstructing the growth curves and body size evolution of different species. A major component of this research focuses on testing if hypothesized indicators of ontogenetic age and growth are recorded similarly across different bones of the same skeleton, different individuals of the same species, and across different species, to what extent each varies, and if that variation follows any particular pattern and/or introduces a sufficient amount of 'noise' to overprint the 'signal' of growth. Based on these data, I have also examined questions of macroevolution, in particular testing differences in growth pattern across dinosaur groups which have independently evolved 'gigantic' body size.
In my current research, I am also combining these approaches with isotopic analyses to investigate events and ecology recorded during the life history of individual animals to reconstruct climate conditions at very fine scales and to test questions such as I) how did seasonal and multi-year patterns of environmental change impact growth of organisms, II) how did diets shift through life, III) how did migration and range-size differ in juveniles vs. adults of a species, and IV) what can we learn about particular behaviors such as parental care in extinct animals?
Most relevant papers (in addition to in-progress research):
Cullen, TM., Brown, CM., Chiba, K., Brink, KS., Makovicky, PJ., Evans, DC. (2021). Growth variability, dimensional scaling, and the interpretation of osteohistological data. Biology Letters 17: 202110383. doi: https://doi.org/10.1098/rsbl.2021.0383
Cullen, TM., Canale, JI., Apesteguía, S., Smith, NS., Hu, D., Makovicky, PJ. (2020). Osteohistological analyses reveal diverse strategies of theropod dinosaur body-size evolution. Proceedings of the Royal Society B 287: 20202258. http://dx.doi.org/10.1098/rspb.2020.2258.
Cullen, TM., Ryan, MJ., Currie, PJ., Kobayashi, Y., and Evans, DC. (2014). Osteohistological variation in growth marks and osteocyte lacunar density in a theropod dinosaur (Coelurosauria: Ornithomimidae). BMC Evolutionary Biology. doi: 10.1186/s12862-014-0231-y.
This research involves quantifying the variability present in multiple growth proxies (e.g. tissue organization, presence of annual growth marks, etc) found in bone microstructure and reconstructing the growth curves and body size evolution of different species. A major component of this research focuses on testing if hypothesized indicators of ontogenetic age and growth are recorded similarly across different bones of the same skeleton, different individuals of the same species, and across different species, to what extent each varies, and if that variation follows any particular pattern and/or introduces a sufficient amount of 'noise' to overprint the 'signal' of growth. Based on these data, I have also examined questions of macroevolution, in particular testing differences in growth pattern across dinosaur groups which have independently evolved 'gigantic' body size.
In my current research, I am also combining these approaches with isotopic analyses to investigate events and ecology recorded during the life history of individual animals to reconstruct climate conditions at very fine scales and to test questions such as I) how did seasonal and multi-year patterns of environmental change impact growth of organisms, II) how did diets shift through life, III) how did migration and range-size differ in juveniles vs. adults of a species, and IV) what can we learn about particular behaviors such as parental care in extinct animals?
Most relevant papers (in addition to in-progress research):
Cullen, TM., Brown, CM., Chiba, K., Brink, KS., Makovicky, PJ., Evans, DC. (2021). Growth variability, dimensional scaling, and the interpretation of osteohistological data. Biology Letters 17: 202110383. doi: https://doi.org/10.1098/rsbl.2021.0383
Cullen, TM., Canale, JI., Apesteguía, S., Smith, NS., Hu, D., Makovicky, PJ. (2020). Osteohistological analyses reveal diverse strategies of theropod dinosaur body-size evolution. Proceedings of the Royal Society B 287: 20202258. http://dx.doi.org/10.1098/rspb.2020.2258.
Cullen, TM., Ryan, MJ., Currie, PJ., Kobayashi, Y., and Evans, DC. (2014). Osteohistological variation in growth marks and osteocyte lacunar density in a theropod dinosaur (Coelurosauria: Ornithomimidae). BMC Evolutionary Biology. doi: 10.1186/s12862-014-0231-y.
IV) Other research topics (collaborative & side-projects contributing to primary research)
I am also actively involved in collaborative research examining: I) sources of preservational, sampling, and analytical biases in studies of the fossil record, II) taphonomic/sedimentological analysis, III) dinosaur biodiversity, anatomy, and taxonomy, IV) morphological variability, sexual dimorphism, and evolution in mammals, and V) the value of natural history data & museums for science and education.
Most relevant papers (in addition to in-progress research):
Nanglu, K., de Carle, D., Cullen, TM., Anderson, E., Arif, S., Castañeda, RA., Chang, LM., Iwama, RE., Fellin, E., Manglicmot, RC., Massey, MD., Astudillo-Clavijo, V. (2023). The nature of science: the fundamental role of natural history in ecology, evolution, conservation and education. Ecology & Evolution 13(10): e10621. doi: https://doi.org/10.1002/ece3.10621
Nanglu, K., Cullen, TM. (2023). Across space and time: a review of sampling, preservational, analytical, and anthropogenic biases in fossil data across macroecological scales. Earth Science Reviews 244. https://doi.org/10.1016/j.earscirev.2023.104537
Cullen, TM., Larson., DW., Witton, MP., Scott, D., Maho, T., Brink, KS., Evans, DC., Reisz, R. (2023). Theropod dinosaur facial reconstruction and the significance of soft tissues in paleobiology. Science 379 (6639): 1348-1352.
Canale, JI., Apesteguía, S., Gallina, PA., Mitchell, J., Smith, ND., Cullen, TM., Shinya, A., Haluza, A., Gianechini, FA., Makovicky, PJ. (2022). New giant carnivorous dinosaur from the Late Cretaceous of Argentina reveals convergent evolutionary trends in theropod arm reduction. Current Biology 32, 1-8. https://doi.org/10.1016/j.cub.2022.05.057
Benson, R., Brown, CM., Campione, N., Cullen, TM., Evans, DC., Zanno, L. (2022). Comment on the influence of juvenile dinosaurs on community structure and diversity. Science 375(657821). doi: https://doi.org/10.1126/science.abj5976
Cullen, TM., Zanno, L., Larson, DW., Todd, E., Currie, PJ., Evans, DC. (2021). Anatomical, morphometric, and stratigraphic review of theropod biodiversity in the Dinosaur Park Formation (Late Cretaceous; Campanian) of Alberta. Canadian Journal of Earth Sciences 58(9): 870-884.
Cullen, TM., Fraser, D., Rybczynski, N., and Schroder-Adams, C. (2014). Early evolution of sexual dimorphism and polygyny in Pinnipedia. Evolution 68-5: 1469–1484. doi: https://dx.doi.org/10.1111/evo.12360
Most relevant papers (in addition to in-progress research):
Nanglu, K., de Carle, D., Cullen, TM., Anderson, E., Arif, S., Castañeda, RA., Chang, LM., Iwama, RE., Fellin, E., Manglicmot, RC., Massey, MD., Astudillo-Clavijo, V. (2023). The nature of science: the fundamental role of natural history in ecology, evolution, conservation and education. Ecology & Evolution 13(10): e10621. doi: https://doi.org/10.1002/ece3.10621
Nanglu, K., Cullen, TM. (2023). Across space and time: a review of sampling, preservational, analytical, and anthropogenic biases in fossil data across macroecological scales. Earth Science Reviews 244. https://doi.org/10.1016/j.earscirev.2023.104537
Cullen, TM., Larson., DW., Witton, MP., Scott, D., Maho, T., Brink, KS., Evans, DC., Reisz, R. (2023). Theropod dinosaur facial reconstruction and the significance of soft tissues in paleobiology. Science 379 (6639): 1348-1352.
Canale, JI., Apesteguía, S., Gallina, PA., Mitchell, J., Smith, ND., Cullen, TM., Shinya, A., Haluza, A., Gianechini, FA., Makovicky, PJ. (2022). New giant carnivorous dinosaur from the Late Cretaceous of Argentina reveals convergent evolutionary trends in theropod arm reduction. Current Biology 32, 1-8. https://doi.org/10.1016/j.cub.2022.05.057
Benson, R., Brown, CM., Campione, N., Cullen, TM., Evans, DC., Zanno, L. (2022). Comment on the influence of juvenile dinosaurs on community structure and diversity. Science 375(657821). doi: https://doi.org/10.1126/science.abj5976
Cullen, TM., Zanno, L., Larson, DW., Todd, E., Currie, PJ., Evans, DC. (2021). Anatomical, morphometric, and stratigraphic review of theropod biodiversity in the Dinosaur Park Formation (Late Cretaceous; Campanian) of Alberta. Canadian Journal of Earth Sciences 58(9): 870-884.
Cullen, TM., Fraser, D., Rybczynski, N., and Schroder-Adams, C. (2014). Early evolution of sexual dimorphism and polygyny in Pinnipedia. Evolution 68-5: 1469–1484. doi: https://dx.doi.org/10.1111/evo.12360
Peer-Reviewed Publications
N=37; 18 first authored, 19 co-authored; * = advised student/postdoc/mentee author
SUBMITTED / IN REVIEW
37. *Caputo, C., King, DT., Cullen, TM. (In Review). A case study of the potential impacts of sampling bias in paleobiological analyses using the Late Cretaceous fossil record of Alabama, USA. Under Review at Acta Palaeontologica Polonica. (initial round of review)
36. *Galinger, MR., Vachula, RS., Goertzen, LR., Hansen, CJ., Cullen, TM. (In Review). A new approach to experimental charcoal analyses: quantifications of intra-plant variability and implications for applications to Cretaceous greenhouse systems. Under Review at Global and Planetary Change. (initial round of review)
35. Cullen, TM., Goodwin, MB., Horner., JR., Stanton, KJ., Spero, HJ., Silva., SR., Carlson, SJ. (In Review). Intra-bone d18O variation supports heterothermy and greater body temperature range than previously reported in Tyrannosaurus rex. Under Review at Geochimica et Cosmochimica acta. (initial round of review)
34. Woodruff, DC., Hone, DWE., Cullen, TM., Simon, DJ., Evans, DC. (In Review). Paleontology and sedimentology of the Acheroraptor holotype locality, a multi-taxic bonebed in the Hell Creek Formation of Montana, USA. Under Review at Science. (re-submitted post-review)
33. Wilkinson, RD., Cullen, TM., Avrahami, H., Zanno, L., Evans, DC. (In Review). Paleontology and sedimentology of the Acheroraptor holotype locality, a multi-taxic bonebed in the Hell Creek Formation of Montana, USA. Under Review at Palaios. (re-submitted post-review)
ACCEPTED / IN PRESS
32. Cullen, TM., Dunn, R., Suarez, C., Chiba, K. (Accepted). Chp. 2.5: Studying Ecosystems. In The Complete Dinosaur, 3rd Edition. Edited by L. Zanno, T. Holtz, and V. Arbour. Indiana University Press.
PUBLISHED
31. *Thompson, M., Cullen, TM., Schröder-Adams, C., Ryan, MJ. (2024). Multi-proxy palaeoenvironmental and palaeoecological reconstruction of the Foremost Formation (Upper Cretaceous; Campanian) of Alberta. Palaios 39(12): 425-443. doi: 10.1177/09596836241274975
30. Vachula, RS., Cullen, TM., *Galinger, MR., *Welch. CJ., Battaglia, J., Smith, D., Waters, MN. (2024). Morphometric characteristics of charcoal produced from plants endemic to the southeastern Unites States of America. The Holocene. doi: 10.1177/09596836241274975
29. *Bhat, MS., Cullen, TM. (2024). Growth and life history of freshwater turtles (Testudines: Cryptodira): a bone histology approach. Journal of Anatomy. doi: 10.1111/joa.14130
28. Cullen, TM., Cousens, B. (2024). Geochemical insights into Mesozoic terrestrial paleoecology and evidence for omnivory in troodontids. GSA Bulletin. https://doi.org/10.1130/B37077.1
27. Nanglu, K., de Carle, D., Cullen, TM., Anderson, E., Arif, S., Castañeda, RA., Chang, LM., Iwama, RE., Fellin, E., Manglicmot, RC., Massey, MD., Astudillo-Clavijo, V. (2023). The nature of science: the fundamental role of natural history in ecology, evolution, conservation and education. Ecology & Evolution 13(10): e10621. doi: https://doi.org/10.1002/ece3.10621
26. Cullen, TM. (2023). Chp. 13: Stable isotopic analyses of living and extinct crocodylians: implications for understanding their ecology, environments, and physiology. In Ruling Reptiles: Crocodylian Biology and Archosaur Paleobiology. Edited by H Woodward and J Farlow. Indiana University Press.
25. Nanglu, K., Cullen, TM. (2023). Across space and time: a review of sampling, preservational, analytical, and anthropogenic biases in fossil data across macroecological scales. Earth Science Reviews 244. https://doi.org/10.1016/j.earscirev.2023.104537
24. Cullen, TM., Larson, DW., Witton, MP., Scott, D., Maho, T., Brink, KS., Evans, DC., Reisz, R. (2023). Theropod dinosaur facial reconstruction and the significance of soft tissues in paleobiology. Science 379 (6639): 1348-1351. (Featured as a 'highlighted article' in Science Magazine)
23. Cullen, TM., Longstaffe, FJ., Wortmann, UG., Huang, L., Evans, DC. (2023). Anomalous 13C-enrichment in Mesozoic vertebrate enamel reflects environmental conditions in a ‘vanished world’ and not a unique dietary physiology. Paleobiology: 1-15.
doi: 10.1017/pab.2022.43
22. Chinzorig, T., Cullen, TM., Phillips, G., Rolke, R., Zanno, LE. (2022). Large-bodied ornithomimosaurs inhabited Appalachia during the Late Cretaceous of North America. PLoS ONE. https://doi.org/10.1371/journal.pone.0266648.
21. Canale, JI., Apesteguía, S., Gallina, PA., Mitchell, J., Smith, ND., Cullen, TM., Shinya, A., Haluza, A., Gianechini, FA., Makovicky, PJ. (2022). New giant carnivorous dinosaur from the Late Cretaceous of Argentina reveals convergent evolutionary trends in theropod arm reduction. Current Biology 32, 1-8. https://doi.org/10.1016/j.cub.2022.05.057
20. Cullen, TM., Zhang, S., Spencer, J., Cousens, B. (2022). Sr-C-O isotope signatures reveal herbivore niche-partitioning in a Cretaceous ecosystem. Palaeontology. doi: https://doi.org/10.1111/pala/12591
19. Benson, R., Brown, CM., Campione, N., Cullen, TM., Evans, DC., Zanno, L. (2022). Comment on the influence of juvenile dinosaurs on community structure and diversity. Science 375(657821). doi: https://doi.org/10.1126/science.abj5976
18. Cullen, TM., Brown, CM., Chiba, K., Brink, KS., Makovicky, PJ., Evans, DC. (2021). Growth variability, dimensional scaling, and the interpretation of osteohistological data. Biology Letters 17: 202110383. doi: https://doi.org/10.1098/rsbl.2021.0383
17. Cullen, TM., Zanno, L., Larson, DW., Todd, E., Currie, PJ., Evans, DC. (2021). Anatomical, morphometric, and stratigraphic review of theropod biodiversity in the Dinosaur Park Formation (Late Cretaceous; Campanian) of Alberta. Canadian Journal of Earth Sciences 58(9): 870-884.
16. Cullen, TM., Canale, JI., Apesteguía, S., Smith, NS., Hu, D., Makovicky, PJ. (2020). Osteohistological analyses reveal diverse strategies of theropod dinosaur body-size evolution. Proceedings of the Royal Society B 287: 20202258. http://dx.doi.org/10.1098/rspb.2020.2258.
15. Cullen, TM., Longstaffe, FJ., Wortmann, UG., Huang, L., Fanti, F., Goodwin, MB., Ryan, MJ., Evans, DC. (2020). Large-scale stable isotope characterization of a Late Cretaceous dinosaur-dominated ecosystem. Geology 48(6): 546-551. (Featured Article & subject of GSA blog)
14. Cullen, TM., Simon, DJ., Benner, EKC., Evans, DC. (2020). Morphology and osteohistology of a large-bodied caenagnathid (Theropoda: Oviraptorosauria) from the Hell Creek Formation (Montana): implications for size-based classifications and growth estimation in theropods. Papers in Palaeontology. https://doi.org/10.1002/spp2/1302
13. Arbour, VM., Evans, DC., Simon, DJ., Cullen, TM., Braman, D. (2019). Cretaceous flora and fauna of the Sustut Group near the Sustut River, northern British Columbia, Canada. Canadian Journal of Earth Sciences. https://doi.org/10.1139/cjes-2019-0031.
12. Cullen, TM., Longstaffe, FJ., Wortmann, UG., Goodwin, MB., Huang, L., and Evans, DC. (2019). Stable isotopic characterization of a coastal floodplain forest community: a case-study for isotopic reconstruction of Mesozoic vertebrate assemblages. Royal Society Open Science 6: 181210. http://dx.doi.org/10.1098/rsos.181210.
11. McFeeters, B., Ryan, MJ., and Cullen, TM. (2018). Response to Brownstein (2018) 'Rebuttal of McFeeters, Ryan and Cullen, 2018'. Vertebrate Anatomy Morphology Palaeontology 6: 73-74. dx.doi.org/10.18435/vamp29343
10. McFeeters, B., Ryan, MJ., and Cullen, TM. (2018). Positional variation in pedal unguals of North American ornithomimids (Dinosauria, Theropoda): a response to Brownstein (2017) . Vertebrate Anatomy Morphology Palaeontology 5. doi: 10.18435/vamp29283
9. LeBlanc, ARH., Brink, K., Cullen, TM., and Reisz, R. (2017). Evolutionary implications of tooth attachment versus tooth implantation: a case study using dinosaur, crocodilian, and mammal teeth. Journal of Vertebrate Paleontology. doi: 10.1080/02724634.2017.1354006
8. Evans, DC., Cullen, TM., Larson, DW., and Rego, A. (2017). A new species of troodontid theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada. Canadian Journal of Earth Sciences. doi: 10.1139/cjes-2017-0034 (Postprint available on PaleorXiv: https://paleorxiv.org/b8mqe/)
7. Cullen, TM. and Evans, DC. (2016). Palaeoenvironmental drivers of vertebrate community composition in the Belly River Group (Campanian) of Alberta, Canada, with implications for dinosaur biogeography. BMC Ecology. doi: 10.1186/s12898-016-0106-8 (Editor's Pick and BMC Ecology top 10 highlight for 2016, and subject of a BMC Series blog)
6. McFeeters, B., Ryan, MJ., Schröder-Adams, C., and Cullen, TM. (2016). A new ornithomimid theropod from the Dinosaur Park Formation of Alberta, Canada. Journal of Vertebrate Paleontology. doi: 10.1080/02724634.2016.1221415
5. Cullen, TM., Fanti, F., Capobianco, C., Ryan, MJ., and Evans, DC. (2016). A vertebrate microsite from a marine-terrestrial transition in the Foremost Formation (Campanian) of Alberta, Canada, and the use of faunal assemblage data as a palaeoenvironmental indicator. Palaeogeography, Palaeoclimatology, Palaeoecology 444: 101-114. doi:10.1016/j.palaeo.2015.12.015 (Postprint available on PaleorXiv: https://paleorxiv.org/43j7z/)
4. Cullen, TM., Ryan, MJ., Currie, PJ., Kobayashi, Y., and Evans, DC. (2014). Osteohistological variation in growth marks and osteocyte lacunar density in a theropod dinosaur (Coelurosauria: Ornithomimidae). BMC Evolutionary Biology. doi: 10.1186/s12862-014-0231-y. (Editor’s Pick and a BMC series highlight for November 2014, and included in list of the 12 best figures in BMC Evolutionary Biology for 2014)
3. Evans, DC., Larson, DW., Cullen, TM., & Sullivan, RM. (2014). "Saurornitholestes" robustus is a troodontid (Dinosauria: Theropoda). Canadian Journal of Earth Sciences 51(7): 730-734. doi: 10.1139/cjes-2014-0073
2. Cullen, TM., Fraser, D., Rybczynski, N., and Schroder-Adams, C. (2014). Early evolution of sexual dimorphism and polygyny in Pinnipedia. Evolution 68-5: 1469–1484. (Subject of the May 2014 cover of Evolution) doi: https://dx.doi.org/10.1111/evo.12360 (Postprint available on PaleorXiv: https://paleorxiv.org/zgh62/)
1. Cullen TM., Ryan MJ, Schröder-Adams C, Currie PJ, Kobayashi Y. (2013). An Ornithomimid (Dinosauria) Bonebed from the Late Cretaceous of Alberta, with Implications for the Behavior, Classification, and Stratigraphy of North American Ornithomimids. PLoS ONE 8(3): e58853. doi:10.1371/journal.pone.0058853
37. *Caputo, C., King, DT., Cullen, TM. (In Review). A case study of the potential impacts of sampling bias in paleobiological analyses using the Late Cretaceous fossil record of Alabama, USA. Under Review at Acta Palaeontologica Polonica. (initial round of review)
36. *Galinger, MR., Vachula, RS., Goertzen, LR., Hansen, CJ., Cullen, TM. (In Review). A new approach to experimental charcoal analyses: quantifications of intra-plant variability and implications for applications to Cretaceous greenhouse systems. Under Review at Global and Planetary Change. (initial round of review)
35. Cullen, TM., Goodwin, MB., Horner., JR., Stanton, KJ., Spero, HJ., Silva., SR., Carlson, SJ. (In Review). Intra-bone d18O variation supports heterothermy and greater body temperature range than previously reported in Tyrannosaurus rex. Under Review at Geochimica et Cosmochimica acta. (initial round of review)
34. Woodruff, DC., Hone, DWE., Cullen, TM., Simon, DJ., Evans, DC. (In Review). Paleontology and sedimentology of the Acheroraptor holotype locality, a multi-taxic bonebed in the Hell Creek Formation of Montana, USA. Under Review at Science. (re-submitted post-review)
33. Wilkinson, RD., Cullen, TM., Avrahami, H., Zanno, L., Evans, DC. (In Review). Paleontology and sedimentology of the Acheroraptor holotype locality, a multi-taxic bonebed in the Hell Creek Formation of Montana, USA. Under Review at Palaios. (re-submitted post-review)
ACCEPTED / IN PRESS
32. Cullen, TM., Dunn, R., Suarez, C., Chiba, K. (Accepted). Chp. 2.5: Studying Ecosystems. In The Complete Dinosaur, 3rd Edition. Edited by L. Zanno, T. Holtz, and V. Arbour. Indiana University Press.
PUBLISHED
31. *Thompson, M., Cullen, TM., Schröder-Adams, C., Ryan, MJ. (2024). Multi-proxy palaeoenvironmental and palaeoecological reconstruction of the Foremost Formation (Upper Cretaceous; Campanian) of Alberta. Palaios 39(12): 425-443. doi: 10.1177/09596836241274975
30. Vachula, RS., Cullen, TM., *Galinger, MR., *Welch. CJ., Battaglia, J., Smith, D., Waters, MN. (2024). Morphometric characteristics of charcoal produced from plants endemic to the southeastern Unites States of America. The Holocene. doi: 10.1177/09596836241274975
29. *Bhat, MS., Cullen, TM. (2024). Growth and life history of freshwater turtles (Testudines: Cryptodira): a bone histology approach. Journal of Anatomy. doi: 10.1111/joa.14130
28. Cullen, TM., Cousens, B. (2024). Geochemical insights into Mesozoic terrestrial paleoecology and evidence for omnivory in troodontids. GSA Bulletin. https://doi.org/10.1130/B37077.1
27. Nanglu, K., de Carle, D., Cullen, TM., Anderson, E., Arif, S., Castañeda, RA., Chang, LM., Iwama, RE., Fellin, E., Manglicmot, RC., Massey, MD., Astudillo-Clavijo, V. (2023). The nature of science: the fundamental role of natural history in ecology, evolution, conservation and education. Ecology & Evolution 13(10): e10621. doi: https://doi.org/10.1002/ece3.10621
26. Cullen, TM. (2023). Chp. 13: Stable isotopic analyses of living and extinct crocodylians: implications for understanding their ecology, environments, and physiology. In Ruling Reptiles: Crocodylian Biology and Archosaur Paleobiology. Edited by H Woodward and J Farlow. Indiana University Press.
25. Nanglu, K., Cullen, TM. (2023). Across space and time: a review of sampling, preservational, analytical, and anthropogenic biases in fossil data across macroecological scales. Earth Science Reviews 244. https://doi.org/10.1016/j.earscirev.2023.104537
24. Cullen, TM., Larson, DW., Witton, MP., Scott, D., Maho, T., Brink, KS., Evans, DC., Reisz, R. (2023). Theropod dinosaur facial reconstruction and the significance of soft tissues in paleobiology. Science 379 (6639): 1348-1351. (Featured as a 'highlighted article' in Science Magazine)
23. Cullen, TM., Longstaffe, FJ., Wortmann, UG., Huang, L., Evans, DC. (2023). Anomalous 13C-enrichment in Mesozoic vertebrate enamel reflects environmental conditions in a ‘vanished world’ and not a unique dietary physiology. Paleobiology: 1-15.
doi: 10.1017/pab.2022.43
22. Chinzorig, T., Cullen, TM., Phillips, G., Rolke, R., Zanno, LE. (2022). Large-bodied ornithomimosaurs inhabited Appalachia during the Late Cretaceous of North America. PLoS ONE. https://doi.org/10.1371/journal.pone.0266648.
21. Canale, JI., Apesteguía, S., Gallina, PA., Mitchell, J., Smith, ND., Cullen, TM., Shinya, A., Haluza, A., Gianechini, FA., Makovicky, PJ. (2022). New giant carnivorous dinosaur from the Late Cretaceous of Argentina reveals convergent evolutionary trends in theropod arm reduction. Current Biology 32, 1-8. https://doi.org/10.1016/j.cub.2022.05.057
20. Cullen, TM., Zhang, S., Spencer, J., Cousens, B. (2022). Sr-C-O isotope signatures reveal herbivore niche-partitioning in a Cretaceous ecosystem. Palaeontology. doi: https://doi.org/10.1111/pala/12591
19. Benson, R., Brown, CM., Campione, N., Cullen, TM., Evans, DC., Zanno, L. (2022). Comment on the influence of juvenile dinosaurs on community structure and diversity. Science 375(657821). doi: https://doi.org/10.1126/science.abj5976
18. Cullen, TM., Brown, CM., Chiba, K., Brink, KS., Makovicky, PJ., Evans, DC. (2021). Growth variability, dimensional scaling, and the interpretation of osteohistological data. Biology Letters 17: 202110383. doi: https://doi.org/10.1098/rsbl.2021.0383
17. Cullen, TM., Zanno, L., Larson, DW., Todd, E., Currie, PJ., Evans, DC. (2021). Anatomical, morphometric, and stratigraphic review of theropod biodiversity in the Dinosaur Park Formation (Late Cretaceous; Campanian) of Alberta. Canadian Journal of Earth Sciences 58(9): 870-884.
16. Cullen, TM., Canale, JI., Apesteguía, S., Smith, NS., Hu, D., Makovicky, PJ. (2020). Osteohistological analyses reveal diverse strategies of theropod dinosaur body-size evolution. Proceedings of the Royal Society B 287: 20202258. http://dx.doi.org/10.1098/rspb.2020.2258.
15. Cullen, TM., Longstaffe, FJ., Wortmann, UG., Huang, L., Fanti, F., Goodwin, MB., Ryan, MJ., Evans, DC. (2020). Large-scale stable isotope characterization of a Late Cretaceous dinosaur-dominated ecosystem. Geology 48(6): 546-551. (Featured Article & subject of GSA blog)
14. Cullen, TM., Simon, DJ., Benner, EKC., Evans, DC. (2020). Morphology and osteohistology of a large-bodied caenagnathid (Theropoda: Oviraptorosauria) from the Hell Creek Formation (Montana): implications for size-based classifications and growth estimation in theropods. Papers in Palaeontology. https://doi.org/10.1002/spp2/1302
13. Arbour, VM., Evans, DC., Simon, DJ., Cullen, TM., Braman, D. (2019). Cretaceous flora and fauna of the Sustut Group near the Sustut River, northern British Columbia, Canada. Canadian Journal of Earth Sciences. https://doi.org/10.1139/cjes-2019-0031.
12. Cullen, TM., Longstaffe, FJ., Wortmann, UG., Goodwin, MB., Huang, L., and Evans, DC. (2019). Stable isotopic characterization of a coastal floodplain forest community: a case-study for isotopic reconstruction of Mesozoic vertebrate assemblages. Royal Society Open Science 6: 181210. http://dx.doi.org/10.1098/rsos.181210.
11. McFeeters, B., Ryan, MJ., and Cullen, TM. (2018). Response to Brownstein (2018) 'Rebuttal of McFeeters, Ryan and Cullen, 2018'. Vertebrate Anatomy Morphology Palaeontology 6: 73-74. dx.doi.org/10.18435/vamp29343
10. McFeeters, B., Ryan, MJ., and Cullen, TM. (2018). Positional variation in pedal unguals of North American ornithomimids (Dinosauria, Theropoda): a response to Brownstein (2017) . Vertebrate Anatomy Morphology Palaeontology 5. doi: 10.18435/vamp29283
9. LeBlanc, ARH., Brink, K., Cullen, TM., and Reisz, R. (2017). Evolutionary implications of tooth attachment versus tooth implantation: a case study using dinosaur, crocodilian, and mammal teeth. Journal of Vertebrate Paleontology. doi: 10.1080/02724634.2017.1354006
8. Evans, DC., Cullen, TM., Larson, DW., and Rego, A. (2017). A new species of troodontid theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada. Canadian Journal of Earth Sciences. doi: 10.1139/cjes-2017-0034 (Postprint available on PaleorXiv: https://paleorxiv.org/b8mqe/)
7. Cullen, TM. and Evans, DC. (2016). Palaeoenvironmental drivers of vertebrate community composition in the Belly River Group (Campanian) of Alberta, Canada, with implications for dinosaur biogeography. BMC Ecology. doi: 10.1186/s12898-016-0106-8 (Editor's Pick and BMC Ecology top 10 highlight for 2016, and subject of a BMC Series blog)
6. McFeeters, B., Ryan, MJ., Schröder-Adams, C., and Cullen, TM. (2016). A new ornithomimid theropod from the Dinosaur Park Formation of Alberta, Canada. Journal of Vertebrate Paleontology. doi: 10.1080/02724634.2016.1221415
5. Cullen, TM., Fanti, F., Capobianco, C., Ryan, MJ., and Evans, DC. (2016). A vertebrate microsite from a marine-terrestrial transition in the Foremost Formation (Campanian) of Alberta, Canada, and the use of faunal assemblage data as a palaeoenvironmental indicator. Palaeogeography, Palaeoclimatology, Palaeoecology 444: 101-114. doi:10.1016/j.palaeo.2015.12.015 (Postprint available on PaleorXiv: https://paleorxiv.org/43j7z/)
4. Cullen, TM., Ryan, MJ., Currie, PJ., Kobayashi, Y., and Evans, DC. (2014). Osteohistological variation in growth marks and osteocyte lacunar density in a theropod dinosaur (Coelurosauria: Ornithomimidae). BMC Evolutionary Biology. doi: 10.1186/s12862-014-0231-y. (Editor’s Pick and a BMC series highlight for November 2014, and included in list of the 12 best figures in BMC Evolutionary Biology for 2014)
3. Evans, DC., Larson, DW., Cullen, TM., & Sullivan, RM. (2014). "Saurornitholestes" robustus is a troodontid (Dinosauria: Theropoda). Canadian Journal of Earth Sciences 51(7): 730-734. doi: 10.1139/cjes-2014-0073
2. Cullen, TM., Fraser, D., Rybczynski, N., and Schroder-Adams, C. (2014). Early evolution of sexual dimorphism and polygyny in Pinnipedia. Evolution 68-5: 1469–1484. (Subject of the May 2014 cover of Evolution) doi: https://dx.doi.org/10.1111/evo.12360 (Postprint available on PaleorXiv: https://paleorxiv.org/zgh62/)
1. Cullen TM., Ryan MJ, Schröder-Adams C, Currie PJ, Kobayashi Y. (2013). An Ornithomimid (Dinosauria) Bonebed from the Late Cretaceous of Alberta, with Implications for the Behavior, Classification, and Stratigraphy of North American Ornithomimids. PLoS ONE 8(3): e58853. doi:10.1371/journal.pone.0058853
Non-Refereed Publications
5. Cullen, T. August 25, 2022. Big head, small arms. Article for The Conversation.
https://theconversation.com/big-head-small-arms-a-newly-discovered-gigantic-dinosaur-evolved-in-a-similar-manner-to-tyrannosaurus-rex-188678
4. Cullen, T. January 10, 2017. Dinosaur distributions in the Belly River. Blog for BMC Series blog. http://blogs.biomedcentral.com/bmcseriesblog/2017/01/10/dinosaur-distributions-belly-river/
3. Cullen, T. July 9, 2016. Microsites and Macroinferences. Blog for 'Valley of the Last Dinosaurs' project of Denver Museum of Nature & Science and the Howard Hughes Medical Institute. http://lastdinos.livesci.org/field-notebook/7/9/microsites-and-macroinferences
2. Cullen, T. July 7, 2016. Field Camps in Many Shapes and Sizes. Blog for 'Valley of the Last Dinosaurs' project of Denver Museum of Nature & Science and the Howard Hughes Medical Institute. http://lastdinos.livesci.org/field-notebook/7/7/field-camps-in-many-shapes-and-sizes
1. Cullen, T. November 19, 2014. Photography in the Field: equal parts business & pleasure. Royal Ontario Museum blogs. https://www.rom.on.ca/en/blog/photography-in-the-field-equal-parts-business-pleasure
https://theconversation.com/big-head-small-arms-a-newly-discovered-gigantic-dinosaur-evolved-in-a-similar-manner-to-tyrannosaurus-rex-188678
4. Cullen, T. January 10, 2017. Dinosaur distributions in the Belly River. Blog for BMC Series blog. http://blogs.biomedcentral.com/bmcseriesblog/2017/01/10/dinosaur-distributions-belly-river/
3. Cullen, T. July 9, 2016. Microsites and Macroinferences. Blog for 'Valley of the Last Dinosaurs' project of Denver Museum of Nature & Science and the Howard Hughes Medical Institute. http://lastdinos.livesci.org/field-notebook/7/9/microsites-and-macroinferences
2. Cullen, T. July 7, 2016. Field Camps in Many Shapes and Sizes. Blog for 'Valley of the Last Dinosaurs' project of Denver Museum of Nature & Science and the Howard Hughes Medical Institute. http://lastdinos.livesci.org/field-notebook/7/7/field-camps-in-many-shapes-and-sizes
1. Cullen, T. November 19, 2014. Photography in the Field: equal parts business & pleasure. Royal Ontario Museum blogs. https://www.rom.on.ca/en/blog/photography-in-the-field-equal-parts-business-pleasure
Funding, Support, and Collaboration
I would like to thank the following agencies and institutions for their funding and/or support of my research (detailed amounts and further information available in my CV):
NCSU / OUIP Opportunity Grant program
Auburn University (start-up grant and associated support)
Natural Sciences and Engineering Research Council of Canada (Alexander Graham Bell Canada Graduate Scholarships [MSc & PhD] & Postdoctoral Fellowship)
Government of Ontario (Ontario Graduate Scholarship; Queen Elizabeth II Scholarship for Science and Technology)
Dinosaur Research Institute (project grants, travel funding)
Carleton University (internal scholarships and RA support)
University of Toronto (internal scholarships)
University of Western Ontario Laboratory for Stable Isotope Science (support, training, and use of analytical equipment)
Canadian Museum of Nature (access to collections, permissions to destructively sample materials)
Royal Ontario Museum (access to collections, use of laboratory facilities, permissions to destructively sample materials)
Royal Tyrrell Museum (access to collections, permissions to destructively sample materials)
Field Museum of Natural History (access to collections, permissions to destructively sample materials)
Kenneth C. Griffin Charitable Fund (support for FMNH postdoctoral position)
Friends of the North Carolina Museum of Natural Sciences (support for NCMNS / NCSU postdoctoral position)
Auburn University (start-up grant and associated support)
Natural Sciences and Engineering Research Council of Canada (Alexander Graham Bell Canada Graduate Scholarships [MSc & PhD] & Postdoctoral Fellowship)
Government of Ontario (Ontario Graduate Scholarship; Queen Elizabeth II Scholarship for Science and Technology)
Dinosaur Research Institute (project grants, travel funding)
Carleton University (internal scholarships and RA support)
University of Toronto (internal scholarships)
University of Western Ontario Laboratory for Stable Isotope Science (support, training, and use of analytical equipment)
Canadian Museum of Nature (access to collections, permissions to destructively sample materials)
Royal Ontario Museum (access to collections, use of laboratory facilities, permissions to destructively sample materials)
Royal Tyrrell Museum (access to collections, permissions to destructively sample materials)
Field Museum of Natural History (access to collections, permissions to destructively sample materials)
Kenneth C. Griffin Charitable Fund (support for FMNH postdoctoral position)
Friends of the North Carolina Museum of Natural Sciences (support for NCMNS / NCSU postdoctoral position)