English: Size comparison of various specimens of the large mosasaur Tylosaurus. Note that there are even more species of Tylosaurus than depicted here, but they are not known from sufficient material for size estimation. The diver silhoutte from File:Scuba33.jpg, which is by NOAA and in the public domain.

•   IRScNB R23 Holotype, estimated to be 12 m (39 ft), scaled to a 1.6 m (5.2 ft) skull^[1][2][3]

•   KUVP 5033 The "Bunker" specimen, here restored with a length of approximately 13 m (43 ft). KUVP 5033 has been estimated to be between 12–13 m (39–43 ft) in total length^[4] and has a total skull length of 1.7 m (5.6 ft).^[5] The proportions between the skull and total length of FHSM VP-3 were used to scale KUVP 5033 here.^[5][4]
•   AMNH FR221 Formerly assigned to T. 'dyspelor', this virtually complete specimen has a length of 8.8 m (29 ft)^[6]

•   MM V95 This specimen has a skull length of 1.21 m (4.0 ft). Length estimates for this species are lacking, but the silhouette been based on the above skull length and revised vertebral count.^[7][8]

•   RSM P2588.1 This specimen (nicknamed "Omācīw") has a skull length of 1.32 m (4.3 ft)^[9] and a total length of around 9.75 m (32.0 ft).^[10] The skull was drawn after Jiménez-Huidobro & Caldwell (2019)^[11], with the postcranium being based on T. pembinensis^[8] and T. proriger.^[6]

•   FHSM VP-2209 Specimen with a 1 m (3.3 ft) mandible and a 7.1 m (23 ft) total length.^[4][3]
•   AMNH 1565 Specimen with a 66 cm (2.17 ft) mandible and a 4.7 m (15 ft) total length.^[4][3]

This species may be synonymous with T. nepaeolicus.^[12] All length estimates are based on Everhart (2005).^[13]

•   FHSM VP-13742 Largest specimen. This species has a maximum estimated length of 7 m (23 ft).
•   FHSM VP-2295 Holotype, 5 m (16 ft)
•   FHSM WP-14848 2 m (6.6 ft) long juvenile

This taxon was published in a thesis and is therefore currently invalid.

•   TMP 2014.011.0001 Estimated to measure 6.5 m (21 ft) long.^[14]

1. ↑ Lindgren, Johan (2005). "The first record of Hainosaurus (Reptilia: Mosasauridae) from Sweden". Journal of Paleontology 79 (6): 1157-1165.
2. ↑ Jiménez-Huidobro, Paulina; Caldwell, Michael W. (2016). "Reassessment and reassignment of the early Maastrichtian mosasaur Hainosaurus bernardi Dollo, 1885, to Tylosaurus Marsh, 1872". Journal of Vertebrate Paleontology 36 (3): e1096275.
3. ↑ ^{a b c} Everhart, Mike (2012). Remains of young mosasaurs from the Smoky Hill Chalk (Upper Coniacian-Lower Campanian) of Western Kansas. Oceans of Kansas.
4. ↑ ^{a b c d} Everhart, Michael J. (2002). "New data on cranial measurements and body length of the mosasaur, Tylosaurus nepaeolicus (Squamata; Mosasauridae), from the Niobrara Formation of western Kansas". Transactions of the Kansas Academy of Science 105 (1): 33-43.
5. ↑ ^{a b} Zietlow, Amelia R. (2020). "Craniofacial ontogeny in Tylosaurinae". PeerJ 8: e10145. DOI:10.7717/peerj.10145.
6. ↑ ^{a b} Osborn, Henry Fairfield (1899). "A complete mosasaur skeleton, osseous and cartilaginous". Memoirs of the American Museum of Natural History 1 (4): 167-188.
7. ↑ Bullard, Timon S.; Caldwell, Michael W. (2010). "Redescription and rediagnosis of the tylosaurine mosasaur Hainosaurus pembinensis Nicholls, 1988, as Tylosaurus pembinensis (Nicholls, 1988)". Journal of Vertebrate Paleontology 30 (2): 416-426.
8. ↑ ^{a b} Hartman, Scott (2015). Tylosaurus pembinensis. Skeletal Drawing.
9. ↑ Jiménez-Huidobro, Paulina; Caldwell, Michael W.; Paparella, Ilaria; Bullard, Timon S. (2019). "A new species of tylosaurine mosasaur from the upper Campanian Bearpaw Formation of Saskatchewan, Canada". Journal of Systematic Palaeontology 17 (10): 849-864.
10. ↑ Omācīw. Royal Saskatchewan Museum. Royal Saskatchewan Museum (2020).
11. ↑ Jiménez-Huidobro, P.; Caldwell, M. W. (2019). "A New Hypothesis of the Phylogenetic Relationships of the Tylosaurinae (Squamata: Mosasauroidea)". Frontiers in Earth Science 7: 47. DOI:10.3389/feart.2019.00047.
12. ↑ Jiménez-Huidobro, Paulina; Simoes, Tiago R. Simoes; Caldwell, Michael W. (2016). "Re-characterization of Tylosaurus nepaeolicus (Cope, 1874) and Tylosaurus kansasensis Everhart, 2005: Ontogeny or sympatry?". Cretaceous Research 65: 68-81.
13. ↑ Everhart, Michael J. (2005). "Tylosaurus kansasensis, a new species of tylosaurine (Squamata, Mosasauridae) from the Niobrara Chalk of western Kansas, USA". Netherlands Journal of Geosciences 84 (3): 231-240.
14. ↑ Garvey, Samuel T. (2020) A new high-latitude Tylosaurus (Squamata, Mosasauridae) from Canada with unique dentition (Thesis)^[1], University of Cincinnati