A new high-latitude Tylosaurus (Squamata, Mosasauridae) from Canada with unique dentition
Bibliographic record
Abstract
Mosasaurs were large aquatic lizards, typically 5 m or more in length, that lived during the Late Cretaceous (ca.100-66 Ma).Of the six subfamilies and more than 70 species recognized today, most were hydropedal (flipper-bearing).Mosasaurs were cosmopolitan apex predators, and their remains occur on every continent, including Antarctica.In North America, mosasaurs flourished in the Western Interior Seaway, an inland sea that covered a large swath of the continent between the Gulf of Mexico and the Arctic Ocean during much of the Late Cretaceous.The challenges of paleontological fieldwork in high latitudes in the Northern Hemisphere have biased mosasaur collections such that most mosasaur fossils are found within 0°-60°N paleolatitude, and in North America plioplatecarpine mosasaurs are the only mosasaurs yet confirmed to have existed in paleolatitudes higher than 60°N.However, this does not mean mosasaur fossils are necessarily lacking at such latitudes.Herein, I report on the northernmost occurrence of a tylosaurine mosasaur from near Grande Prairie in Alberta, Canada (ca. 86.6-79.6Ma).Recovered from about 62°N paleolatitude, this material (TMP 2014.011.0001) is assignable to the subfamily Tylosaurinae by exhibiting a cylindrical rostrum, broadly parallel-sided premaxillo-maxillary sutures, and overall homodonty.I further refer this material to Tylosaurus based on the lack of a dorsal midsagittal ridge on the premaxilla.Unexpectedly, TMP 2014.011.0001exhibits widely spaced, high-aspect-ratio marginal tooth crowns and low-profile maxillae, similar to the typical juvenile condition of Tylosaurus, despite its likely adult age based on an estimated body length of at least 6.5 m.The specimen also exhibits anterior maxillary tooth roots covered by downward extensions of the maxillary cortical bone, a feature previously unknown in Tylosaurinae.TMP 2014.011.0001hints at an undiscovered, temporally more stable my supervisor for this undertaking, and has proved an excellent guide, in both my research and my teaching.I also wish to thank Drs. B. C. Jayne and E. J. Tepe for their thoughtful and incisive advice,
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".