Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Varanopid from the Carboniferous of Nova Scotia reveals evidence of parental care in amniotes


Here we report on a fossil synapsid, Dendromaia unamakiensis gen. et sp. nov., from the Carboniferous period of Nova Scotia that displays evidence of parental care—approximately 40 million years earlier than the previous earliest record based on a varanopid from the Guadalupian (middle Permian) period of South Africa. The specimen, consisting of an adult and associated conspecific juvenile, is also identified as a varanopid suggesting parental care is more deeply rooted within this clade and evolved very close to the origin of Synapsida and Amniota in general. This specimen adds to growing evidence that parental care was more widespread among Palaeozoic synapsids than previously thought and further provides data permitting the identification of potential ontogeny-dependent traits within varanopids, the implications of which impact recent competing hypotheses of the phylogenetic affinities of the group.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Prices vary by article type



Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Locality and horizon information for D. unamakiensis gen. et sp. nov. (NSM017GF020.001).
Fig. 2: Photographs of D. unamakiensis gen. et sp. nov. (NSM017GF020.001).
Fig. 3: Illustrations of D. unamakiensis gen. et sp. nov. (NSM017GF020.001).
Fig. 4: Photographs of the small individual of D. unamakiensis gen. et sp. nov. (NSM017GF020.001).
Fig. 5: Time-calibrated strict consensus tree from the parsimony-based phylogenetic analysis including D. unamakiensis gen. et sp. nov. (NSM017GF020.001).

Data availability

Specimen NSM017GF020.001 is accessioned in the Nova Scotia Museum. See Supplementary Information and Dataset for character list and character–taxon matrix used in the currently analyses.


  1. Drent, R. H. & Daan, S. The prudent parent: energetic adjustments in avian breeding. Ardea 68, 225–252 (1980).

    Google Scholar 

  2. Smiseth, P. T., Kölliker, M. & Royle, N. J. in The Evolution of Parental Care (eds Royle, N. J. et al.) 1–14 (Oxford Univ. Press, 2012).

  3. Jasinoski, S. C. & Abdala, F. Aggregations and parental care in the Early Triassic basal cynodonts Galesaurus planiceps and Thrinaxodon liorhinus. PeerJ 5, e2875 (2017).

    Article  Google Scholar 

  4. Meng, Q., Liu, J., Varricchio, D. J., Huang, T. & Gao, C. Parental care in an ornithischian dinosaur. Nature 431, 145–146 (2004).

    Article  CAS  Google Scholar 

  5. Varricchio, D. J., Martin, A. J. & Katsura, Y. First trace and body fossil of a burrowing, denning dinosaur. Proc. R. Soc. Lond. B 274, 1361–1368 (2007).

    Article  Google Scholar 

  6. Botha-Brink, J. & Modesto, S. P. A mixed-age classed ‘pelycosaur’ aggregation from South Africa: earliest evidence of parental care in amniotes? Proc. R. Soc. Lond. B 274, 2829–2834 (2007).

    Article  Google Scholar 

  7. Lü, J., Kobayashi, Y., Deeming, D. C. & Liu, Y. Post-natal parental care in a Cretaceous diapsid from northeastern China. Geosci. J. 19, 273–280 (2015).

    Article  Google Scholar 

  8. Aleksiuk, M. Cold-induced aggregative behavior in the Red-Sided Garter Snake (Thamnophis sirtalis parietalis). Herpetologica 33, 98–101 (1977).

    Google Scholar 

  9. Rivas, J. A. & Burghardt, G. M. Snake mating systems, behavior, and evolution: the revisionary implications of recent findings. J. Comp. Psychol. 119, 447–454 (2005).

    Article  Google Scholar 

  10. Spindler, F. et al. First arboreal ‘pelycosaurs’ (Synapsida: Varanopidae) from the early Permian Chemnitz Fossil Lagerstätte, SE-Germany, with a review of varanopid phylogeny. Paläont. Zeit. 92, 315–364 (2018).

    Article  Google Scholar 

  11. Reisz, R. R. & Dilkes, D. W. Archaeovenator hamiltonensis, a new varanopid (Synapsida: Eupelycosauria) from the Upper Carboniferous of Kansas. Can. J. Earth Sci. 40, 667–678 (2003).

    Article  Google Scholar 

  12. Haeckel, E. Generelle Morphologie der Organismen (G. Reimer, 1866).

  13. Romer, A. S. & Price, L. I. Review of the Pelycosauria. Geol. Soc. Am. Spec. Pap. 28, 1–538 (1940).

    Google Scholar 

  14. Allen, J. P., Fielding, C. R., Gibling, M. R. & Rygel, M. C. Recognizing products of palaeoclimate fluctuation in the fluvial stratigraphic record: an example from the Pennsylvanian to Lower Permian of Cape Breton Island, Nova Scotia. Sedimentology 61, 1332–1382 (2014).

    Article  Google Scholar 

  15. Berman, D. S. & Reisz, R. R. Restudy of Mycterosaurus longiceps (Reptilia, Pelycosauria) from the Lower Permian of Texas. Ann. Carn. Mus. 51, 423–453 (1982).

    Google Scholar 

  16. Botha-Brink, J. & Modesto, S. P. Anatomy and relationships of the Middle Permian varanopid Heleosaurus scholtzi based on a social aggregation from the Karoo Basin of South Africa. J. Vert. Paleontol. 29, 389–400 (2009).

    Article  Google Scholar 

  17. Reisz, R. R. & Modesto, S. P. Heleosaurus scholtzi from the Permian of South Africa: a varanopid synapsid, not a diapsid reptile. J. Vert. Paleontol. 27, 734–739 (2007).

    Article  Google Scholar 

  18. Carroll, R. L. in Athlon: Essays on Paleontology in Honour of Loris Shano Russell (ed. Churcher, C. S.) 58–79 (Misc. Publ. R. Ont. Mus., 1976).

  19. Anderson, J. S. & Reisz, R. R. Pyozia mesenensis, a new, small varanopid (Synapsida, Eupelycosauria) from Russia: “pelycosaur” diversity in the Middle Permian. J. Vert. Paleontol. 24, 173–179 (2004).

    Article  Google Scholar 

  20. Davies, N. S. & Gibling, M. R. Evolution of fixed-channel alluvial plains in response to Carboniferous vegetation. Nat. Geosci. 4, 629–633 (2011).

    Article  CAS  Google Scholar 

  21. Gibling, M. R. & Davies, N. S. Palaeozoic landscapes shaped by plant evolution. Nat. Geosci. 5, 99–105 (2012).

    Article  CAS  Google Scholar 

  22. Ielpi, A., Gibling, M. R., Bashforth, A. R. & Dennar, C. I. Impact of vegetation on Early Pennsylvanian fluvial channels: insights from the Joggins Formation of Atlantic Canada. J. Sediment. Res. 85, 999–1018 (2015).

    Article  Google Scholar 

  23. Steyer, J. S. Ontogeny and phylogeny in temnospondyls: a new method of analysis. Zool. J. Linn. Soc. 130, 449–467 (2000).

    Article  Google Scholar 

  24. Tsuihiji, T. et al. Cranial osteology of juvenile specimens of Tarbosaurus bataar (Theropoda, Tyrannosauridae) from the Nemegt Formation (Upper Cretaceous of Bugin Tzav, Mongolia). J. Vert. Paleontol. 31, 497–517 (2011).

    Article  Google Scholar 

  25. Campione, N. E., Brink, K. S., Freedman, E. A., McGarrity, C. T. & Evans, D. C. ‘Glishades ericksoni’, an indeterminate juvenile hadrosaurid from the Two Medicine Formation of Montana: implications for hadrosauroid diversity in the latest Cretaceous (Campanian-Maastricthian) of western North America. Palaeobio. Palaeoenv. 93, 65–75 (2013).

    Google Scholar 

  26. Tsai, C. H. & Fordyce, R. E. Juvenile morphology in baleen whale phylogeny. D. Naturwissen. 101, 765–769 (2014).

    Article  CAS  Google Scholar 

  27. Maddin, H. C., Evans, D. C. & Reisz, R. R. An Early Permian varanodontine varanopid (Synapsida: Eupelycosauria) from the Richards Spur Locality, Oklahoma. J. Vert. Paleontol. 26, 957–966 (2006).

    Article  Google Scholar 

  28. Ford, D. P. & Benson, R. A redescription of Orovenator mayorum (Sauropsida, Diapsida) using high-resolution μCT, and the consequences for early amniote phylogeny. Pap. Palaeontol. 5, 197–239 (2019).

    Article  Google Scholar 

  29. Ford, D. P. & Benson, R. B. J. The phylogeny of early amniotes and the affinities of Parareptilia and Varanopidae. Nat. Ecol. Evol. (2019).

  30. Brocklehurst, N. & Fröbisch, J. A reexamination of Milosaurus mccordi, and the evolution of large body size in Carboniferous synapsids. J. Vert. Paleontol. 38, e1508026 (2018).

    Article  Google Scholar 

  31. Swofford, D. L. PAUP*: Phylogenetic Analysis Using Parsimony (*and Other Methods) Version 4.0b8 (Sinauer Associates, 2002).

  32. Ronquist, F. et al. MrBayes 3.2: efficient Bayesian phylogenetic inference and model choice across a large model space. Syst. Biol. 61, 539–542 (2012).

    Article  Google Scholar 

  33. Brocklehurst, N., Reisz, R. R., Fernandez, V. & Fröbisch, J. A re-description of ‘Mycterosaurus’ smithae, an Early Permian eothyridid, and its impact on the phylogeny of pelycosaurian-grade synapsids. PLoS ONE 11, e0156810 (2016).

    Article  Google Scholar 

  34. Fracasso, M. A. Age of the Permo-Carboniferous Cutler Formation vertebrate fauna from El Cobre Canyon, New Mexico. J. Paleontol. 54, 1237–1244 (1980).

    Google Scholar 

  35. Langston, W. Permian amphibian from New Mexico. Univ. Calif. Publ. Geol. Sci. 29, 349–416 (1953).

    Google Scholar 

  36. Vaughn, P. P. The age and locality of the Late Paleozoic vertebrates from El Cobre Canyon, Rio Arriba County, New Mexico. J. Paleontol. 37, 283–286 (1963).

    Google Scholar 

  37. Langston, W. & Reisz, R. R. Aerosaurus wellesi, new species, a varanopseid mammal-like reptile (Synapsida: Pelycosauria) from the Lower Permian of New Mexico. J. Vert. Paleontol. 1, 73–96 (1981).

    Article  Google Scholar 

Download references


We thank T. Fedak, M. Grey, K. Ogden and staff at the Nova Scotia Museum for facilitating the loan of this material. We also thank S. W. McKeane and Provincial staff for assistance with permits. We thank J. Calder, D. Scott, J. Pardo, B. Gee, R. Hook, S. Modesto and R. Reisz for discussions. We thank D. Gray for assistance in the field. We acknowledge our field site is located in Mi’kma’ki territory of the Mi’kmaq people. Funding was provided in part by the Natural Sciences and Engineering Research Council of Canada discovery grant (no. 04633 to H.C.M.).

Author information

Authors and Affiliations



H.C.M. was principal investigator. B.H. discovered the specimen. A.M. and H.C.M. prepared and illustrated the specimen. All authors contributed to discussion, preparation and writing of the manuscript.

Corresponding author

Correspondence to Hillary C. Maddin.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Character list and Supplementary Figs. 1 and 2.

Reporting Summary

Supplementary Dataset

Character–taxon matrix.

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Maddin, H.C., Mann, A. & Hebert, B. Varanopid from the Carboniferous of Nova Scotia reveals evidence of parental care in amniotes. Nat Ecol Evol 4, 50–56 (2020).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing