Zalmoxes

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Zalmoxes
Temporal range: Maastrichtian
70–66  Ma
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Zalmoxes robustus dentary.jpg
Right holotype dentary of Z. robustus from above and the side
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Dinosauria
Clade:† Ornithischia
Clade:† Ornithopoda
Family:† Rhabdodontidae
Genus:† Zalmoxes
Weishampel et al. 2003
Species:
†Z. robustus
Binomial name
†Zalmoxes robustus
Synonyms

Zalmoxes is a genus of probable rhabdodontid ornithopod dinosaur from the Maastrichtian age of the Late Cretaceous in what is now Romania. The genus is known from specimens first named as the species Mochlodon robustum in 1899 by Franz Nopcsa before being reclassified as Rhabdodon robustum by him in 1915. In 1990, this name was corrected to Rhabdodon robustus by George Olshevsky and, in 2003, the species was once more reclassified as the type species Zalmoxes robustus. Zalmoxes represents one of the most common vertebrates of Transylvania during the latest Cretaceous period. [1] The generic name refers to the Dacian deity Zalmoxis and the specific name robustus refers to the robustness of the remains. Another species, Zalmoxes shqiperorum, was named in 2003, but this species has since been reassigned to a separate genus of ceratopsian, Ferenceratops .

Contents

History of discovery

Caudal vertebra, Deva Natural History Museum Zalmoxes vertebra.jpg
Caudal vertebra, Deva Natural History Museum

Zalmoxes was first known from numerous fossils found in Transylvania, which were named as the species Mochlodon robustus by Baron Franz Nopcsa in 1899. The specific name referred to its robust build. [2] In 1915, Nopcsa renamed the species to Rhabdodon robustum, amended in 2003 by David B. Weishampel, Coralia-Maria Jianu, Zoltan Csiki, and David B. Norman. Weishampel et al. (2003) published a paper on new remains from Romania, which they found to represent a new species. They found R. robustus was sufficiently different from Rhabdodon and named the new genus Zalmoxes for the former. The genus refers to the Thracian deity Zalmoxis (sometimes spelled Zalmoxes), who retreated for three years in a crypt to be resurrected on the fourth year. Likewise, the animal Zalmoxes had been liberated from its fossil grave to attain taxonomic immortality. The naming article further explained this by referring to Zalmoxes, a ruler viewed as a deity by the Getae, a Thracian Tribe, according to Herodotus. Weishampel et al. also named new specimens as Zalmoxes shqiperorum, after Shqiperia, the Albanian name for Albania, with which Nopcsa had a special relationship. [3] In 2026, this species was determined to be a ceratopsian dinosaur as opposed to an ornithopod, and given the new generic name Ferenceratops . [4]

One specimen is now assigned to Telmatosaurus , while another specimen is also suspected to belong to that genus based on similar basicrania morphology. [5]

Description

Life restoration Zalmoxes TD.png
Life restoration

Zalmoxes is a rather small genus of bipedal herbivore with a large triangular head and a beak. [3] The subadult Z. robustus range from 2–2.4 m (6.6–7.9 ft) in total body length. [6] An adult Z. robustus would have measured up to 2.5 m (8.2 ft) in length and 45 kg (99 lb) in body mass. [7] An unnamed species of Zalmoxes, is known from larger sizes, with an adult 2.9 m (9.5 ft) in length. Although Nopcsa thought the small size of Zalmoxes was due to island dwarfism, Attila Ösi and colleagues found it was closer to the size of the rhabdodontid ancestor, with larger Rhabdodon and smaller Mochlodon having island gigantism and island dwarfism respectively. [8] [9] [10] However, when the species of Zalmoxes are taken into account separately, it can be seen than Z. shqiperorum continued the general size trend from Orodromeus to Tenontosaurus , while Z. robustus may have had slight nanism. [6] Zalmoxes had a relatively slow growth rate and long growth period, suggesting that this dinosaur may have had a unique growth strategy. [11]

Zalmoxes robustus (purple) compared in size to a human and other iguanodonts Iguanodontian Sizes.svg
Zalmoxes robustus (purple) compared in size to a human and other iguanodonts

Z. robustus is known from about 80% of the skull. However, no complete articulated skull is known, and most of the bones do not overlap and are found in isolation. Weishampel et al. found that these likely represented one individual, as the bones were from the same formation and are the same colour. Four individuals were identified by Nopcsa for Z. robustus, and from these it can be seen that there is skeletal variation in the species. Like with the cranial material, vertebrae of Z. robustus are often found isolated. All regions of the vertebral column are represented in the fossil record, although no sternal plates have been found yet. The sacrum includes three vertebrae, with two sacrodorsals (dorsal vertebrae in the sacrum) and three sacrocaudals (caudal vertebrae in the sacrum). The limb and girdle bones are also well represented, with only the hands (manus) and feet (pes) mostly lacking. [3]

While more poorly known than Z. robustus, Z. shqiperorum is still known from a relatively large amount of the skeleton. Only two mostly complete skeletons are known, the holotype adult, and a referred juvenile. The lower jaw (dentary) of Z. shqiperorum is relatively shorter than the equivalent in Z. robustus, although it is much larger. Ossified tendons are known from the juvenile specimen, showing that they were circular or elliptical in cross section and have fine striations in Z. shqiperorum. Cervical, dorsal and caudal vertebrae are known from Z. shqiperorum, although the former two are only represented by juvenile material. A complete articulated sacrum is known for Z. shqiperorum, with three vertebrae and at least two sacrodorsals. No manual material is known from the species, although a metatarsal and a few phalanges are known. [3]

Classification

Articulated sacrum of Zalmoxes Zalmoxes sacrum.jpg
Articulated sacrum of Zalmoxes

The species of Mochlodon, Rhabdodon and Zalmoxes had long had an uncertain phylogenetic placement, being referred to various families. Nopcsa (1901) also had referred the genus to Hypsilophodontidae, and he suggested affinities with Camptosaurus in 1902, 1904 and 1915. Nopcsa (1915) also realized that Rhabdodon and Mochlodon may be congeneric, placing the complex in Camptosauridae. [3]

For the next half-century, taxonomic workers found Rhabdodon and Mochlodon within either Camptosauridae or Iguanodontidae. However, Paul Sereno (1986) found that Rhabdodon and Mochlodon were within Iguanodontia. The ICZN (1988) resolved this complication, selecting the ornithopod Rhabdodon as having priority over Mochlodon. From this publication, scientists began placing Rhabdodon and Mochlodon within Euornithopoda. In 2003, Weishampel et al. named a new family for Mochlodon, Rhabdodon and the new genus Zalmoxes. This family, Rhabdodontidae, was placed as a derived within Iguanodontia. [3] Further studies support this placement of Rhabdodontidae, phylogenetically between Talenkauen and Tenontosaurus . [6] [12]

Below are two possible phylogenies of Rhabdodontidae by McDonald et al. (2010; left), [12] and Ösi et al. (2012; right). [6]

Ornithopoda

In their phylogenetic analyses of Ajkaceratops and Ferenceratops, Maidment et al. (2026) used the phylogenetic dataset of Han et al. (2017), which was used to test the relationships of the early ceratopsian Yinlong . [13] Their results confidently placed these two genera within the Ceratopsia. In some versions of their phylogenetic analyses, Zalmoxes robustus was retained as an ornithopod, including the extended implied weighting analysis, which recovered a poorly-resolved Ceratopsia but better resolution for early-diverging lineages and ornithopods. Using a Bayesian analysis, Ceratopsia was better resolved, with Zalmoxes robustus forming a distinct clade with Ajkaceratops and Ferenceratops, specifically as the sister taxon to one including Zuniceratops , Turanoceratops , and the more derived Ceratopsidae. This tree, however, recovered an unresolved polytomy at the base of Cerapoda including Pachycephalosauria, Ceratopsia, and most included ornithopod taxa. The results of the Bayesian analysis are displayed in the cladogram below, focused on more derived ceratopsians. [4]

Neoceratopsia

Paleobiology

Restoration of the pterosaur Hatzegopteryx preying on Zalmoxes Hatzegopteryx.png
Restoration of the pterosaur Hatzegopteryx preying on Zalmoxes

Zalmoxes has a more robust build than its precursors and more derived relatives. Infraspecific ontogenetic growth is relatively well known in Zalmoxes as there is juvenile material known for the species. Nopcsa proposed that the animals of the Hateg Basin, which were smaller than their relatives elsewhere, adapted through insular dwarfism. [3] Fossils of both species of Zalmoxes have been unearthed in the Sânpetru Formation, the Sebes Formation and Densuş-Ciula Formation in Romania, both species have been found exclusively in the Hateg Island region. [14]

Diet

A scientific paper from 2003 found that Zalmoxes most likely had a diet that consisted of tough fibrous plants like soft shoots, horsetails, angiosperms, pteridophytes, and ferns. [15] Further studies showed that it could process and digest C3 plants. [16] [17]

References

  1. ↑ Brusatte, Stephen L.; Dumbravă, Mihai; Vremir, Mátyás; Csiki-Sava, Zoltán; Totoianu, Radu; Norell, Mark A. (October 2017). "A Catalog of Zalmoxes (Dinosauria: Ornithopoda) Specimens from the Upper Cretaceous Nălaţ-Vad Locality, Haţeg Basin, Romania". American Museum Novitates (3884): 1–36. doi:10.1206/3884.1. ISSN   0003-0082. Archived from the original on 2024-11-12. Retrieved 2025-04-10.
  2. ↑ Nopcsa, F. (1899). "Dinosaurierreste aus Siebenbürgen (Schädel von Limnosaurus transsylvanicus nov. gen. et spec.), Denkschriften der Kaiserlichen Akademie der Wissenschaften". Mathematisch-Naturwissenschaftliche Classe. 68: 555–591.
  3. 1 2 3 4 5 6 7 Weishampel, D.B.; Jianu, C.-M.; Csiki, Z.; Norman, D.B. (2003). "Osteology and phylogeny of Zalmoxes (n. g.), an unusual euornithopod dinosaur from the Latest Cretaceous of Romania". Journal of Systematic Palaeontology. 1 (2): 65–123. Bibcode:2003JSPal...1...65W. doi:10.1017/S1477201903001032. S2CID   86339025.
  4. 1 2 Maidment, Susannah C. R.; Butler, Richard J.; Brusatte, Stephen L.; Meade, Luke E.; Augustin, Felix J.; Csiki-Sava, Zoltán; Ősi, Attila (2026-10-07). "A hidden diversity of ceratopsian dinosaurs in Late Cretaceous Europe". Nature : 1–7. doi:10.1038/s41586-025-09897-w. ISSN   1476-4687.
  5. ↑ Augustin, F.J.; Dumbravă, M.D.; Bastiaans, D.; Csiki-Sava, Z. (2022). "Reappraisal of the braincase anatomy of the ornithopod dinosaurs Telmatosaurus and Zalmoxes from the Upper Cretaceous of the Haţeg Basin (Romania) and the taxonomic reassessment of some previously referred specimens". PalZ. 97: 129–145. doi: 10.1007/s12542-022-00621-x .
  6. 1 2 3 4 Ősi, A.; Prondvai, E.; Butler, R.; Weishampel, D. B. (2012). Evans, Alistair Robert (ed.). "Phylogeny, Histology and Inferred Body Size Evolution in a New Rhabdodontid Dinosaur from the Late Cretaceous of Hungary". PLOS ONE. 7 (9) e44318. Bibcode:2012PLoSO...744318O. doi: 10.1371/journal.pone.0044318 . PMC   3448614 . PMID   23028518.
  7. ↑ Paul, Gregory S. (2016). The Princeton Field Guide to Dinosaurs. Princeton University Press. p. 312. ISBN   978-1-78684-190-2. OCLC   985402380.
  8. ↑ Benton, Michael J.; Csiki, Zoltan; Grigorescu, Dan; Redelstorff, Ragna; Sander, P. Martin; Stein, Koen; Weishampel, David B. (2010-07-15). "Dinosaurs and the island rule: The dwarfed dinosaurs from Haţeg Island" . Palaeogeography, Palaeoclimatology, Palaeoecology. European island faunas of the Late Cretaceous – The Haţeg Island. 293 (3): 438–454. Bibcode:2010PPP...293..438B. doi:10.1016/j.palaeo.2010.01.026. ISSN   0031-0182.
  9. ↑ Codrea, Vlad; Vremir, Matei; Jipa, Cătălin; Godefroit, Pascal; Csiki, Zoltán; Smith, Thierry; Fărcaş, Cristina (2010-07-15). "More than just Nopcsa's Transylvanian dinosaurs: A look outside the Haţeg Basin" . Palaeogeography, Palaeoclimatology, Palaeoecology. European island faunas of the Late Cretaceous – The Haţeg Island. 293 (3): 391–405. Bibcode:2010PPP...293..391C. doi:10.1016/j.palaeo.2009.10.027. ISSN   0031-0182.
  10. ↑ Weishampel, David B.; Csiki, Zoltán; Benton, Michael J.; Grigorescu, Dan; Codrea, Vlad (2010-07-15). "Palaeobiogeographic relationships of the Haţeg biota — Between isolation and innovation" . Palaeogeography, Palaeoclimatology, Palaeoecology. European island faunas of the Late Cretaceous – The Haţeg Island. 293 (3): 419–437. Bibcode:2010PPP...293..419W. doi:10.1016/j.palaeo.2010.03.024. ISSN   0031-0182.
  11. ↑ Csiki, Z.; Redelstorff, R.; Grigorescu, D. (2009). "Bone histology in the Ornithopods from the Maastrichtian of Haţeg Basin – were these dinosaurs really dwarfs?". In Bucur, I.I.; Săsăran, E.; Popyear, D. (eds.). Proceedings of the 7th Romanian Symposium on Paleontology, Cluj-Napoca, 22-24 October 2009 (PDF). Vol. 7. Cluj University Press. pp. 31–32. doi:10.13039/501100000780. OCLC   800980988.
  12. 1 2 McDonald, A. T.; Kirkland, J. I.; Deblieux, D. D.; Madsen, S. K.; Cavin, J.; Milner, A. R. C.; Panzarin, L. (2010). Farke, Andrew Allen (ed.). "New Basal Iguanodonts from the Cedar Mountain Formation of Utah and the Evolution of Thumb-Spiked Dinosaurs". PLOS ONE. 5 (11) e14075. Bibcode:2010PLoSO...514075M. doi: 10.1371/journal.pone.0014075 . PMC   2989904 . PMID   21124919.
  13. ↑ Han, Fenglu; Forster, Catherine A.; Xu, Xing; Clark, James M. (November 14, 2018). "Postcranial anatomy of Yinlong downsi (Dinosauria: Ceratopsia) from the Upper Jurassic Shishugou Formation of China and the phylogeny of basal ornithischians". Journal of Systematic Palaeontology . 16 (14): 1159–1187. doi:10.1080/14772019.2017.1369185. ISSN   1477-2019.
  14. ↑ Godefroit, Pascal; Codrea, Vlad; Weishampel, David B. (30 September 2009). "Osteology of Zalmoxes shqiperorum (Dinosauria, Ornithopoda), based on new specimens from the Upper Cretaceous of Nalat-Vad (Romania)" . Geodiversitas. 31 (3): 525–553. Bibcode:2009Geodv..31..525G. doi:10.5252/g2009n3a3. S2CID   131476195 . Retrieved 30 October 2020.
  15. ↑ Weishampel, Dave; Csiki-Sava, Zoltan; Norman, David (January 2003). "Osteology and phylogeny of Zalmoxes (n. g.), an unusual Euornithopod dinosaur from the latest Cretaceous of Romania". Journal of Systematic Palaeontology. 1 (2): 65–123. Bibcode:2003JSPal...1...65W. doi:10.1017/S1477201903001032. S2CID   86339025 . Retrieved 24 February 2021.
  16. ↑ Augustin, Felix J.; Ősi, Attila; Csiki-Sava, Zoltán (2023-08-28). "The Rhabdodontidae (Dinosauria, Ornithischia), an enigmatic dinosaur group endemic to the Late Cretaceous European Archipelago". Fossil Record. 26 (2): 171–189. doi: 10.3897/fr.26.108967 . ISSN   2193-0074.
  17. ↑ Bojar, Ana-Voica; Csiki, Zoltan; Grigorescu, Dan (July 2010). "Stable isotope distribution in Maastrichtian vertebrates and paleosols from the Haţeg Basin, South Carpathians". Palaeogeography, Palaeoclimatology, Palaeoecology. 293 (3–4): 329–342. Bibcode:2010PPP...293..329B. doi:10.1016/j.palaeo.2009.08.027. ISSN   0031-0182.
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