Say Goodbye to Kronosaurus!

[Federreptil]

I read this thread with an increasing smile. Much of the commentary deals with the frustration of weak naming and the tragedy of losing a resonant and established name. Now, obviously, the greatest happiness for many paleontologists is when they get to give their find a new name. And many of these new names are not particularly unpresidential or well spoken. Some derivations are also very nerdy or slime the sponsor of the dig. No comparison to the probably planned marketing coup of a 'Tyrannosaurus Rex'. So if the beauty of the name should be criterion for the admissible current state of science, then there would still be some work to do in the marketing of the naming ;-)

On the other hand, many facts, classifications and attributions in paleontology are always only an intermediate state and thus change is possible at any time, if new finds, models or theories change the point of view. Therefore it is worth to wait and to conserve cherished views. Maybe they will come back in a slightly changed form (see Brontosaurus). Or one finds a bunch of upright rebels who resist the mainstream (the birds are not a dinosaur faction), with whom one feels at home. Besides, science is not a one-way street with a single opinion after all. But a cloud of conflicting arguments, which grows just at the contradiction.

So no need to get excited. It is actually just scientific business as usual.

[Sim]

An attempt to establish a neotype for Kronosaurus has begun.  It's covered on the Kronosaurus Wikipedia page.  Apparently, even Eiectus might be non-diagnostic due to its holotype being covered in plaster.  Funny!

[Sim]

Also, it's been put forward that the naming of Eiectus apparently ignored the conclusion of McHenry's thesis that there is only one large pliosaurid in the Toolebuc Formation, meaning that all the remains of such would be of Kronosaurus queenslandicus.  So even without a neotype, Kronosaurus is back to being valid!

[crazy8wizard]

Oooh I gotta keep an eye on the status of this! I'm working on an upcoming presentation about the Harvard Kronosaurus mount, so new information on the status of Eiectus would be helpful.

[BlueKrono]

Oooh I gotta keep an eye on the status of this! I'm working on an upcoming presentation about the Harvard Kronosaurus mount, so new information on the status of Eiectus would be helpful.

I touch on the Harvard Krono in my forthcoming Marx review. I would recommend the book the Rarest of the Rare if you can get your hands on it. It has some interesting details that can't be found online.

[DinoToyForum]

Here's the relevant discussion I think Sim is referring to, quoted from Poropat et al. (2023) (Stephen F. Poropat, Phil R. Bell, Lachlan J. Hart, Steven W. Salisbury & Benjamin P. Kear (2023) An annotated checklist of Australian Mesozoic tetrapods, Alcheringa: An Australasian Journal of Palaeontology, 47:2, 129-205, DOI: 10.1080/03115518.2023.222836) (Apologies for some of the broken formatting)

SAUROPTERYGIA Owen, 1860b
PISTOSAUROIDEA Baur, 1887 in Zittel, 1887–1890 PLESIOSAURIA de Blainville, 1835
PLIOSAURIDAE Seeley, 1874
BRACHAUCHENINAE Williston, 1925 (sensu Benson & Druckenmiller 2014)
Kronosaurus Longman, 1924
Type species
Kronosaurus queenslandicus Longman, 1924, as revised by McHenry (2009).
Kronosaurus queenslandicus Longman, 1924
1924, Kronosaurus queenslandicus Longman, p. 26. 1991, Kronosaurus queenslandicus? Molnar, p. 613. 2022, Eiectus longmani No␘e & Gom␙ez-P␙erez, p. 6.
Type material
QM F1609 (holotype), weathered paired jaw bone fragments containing remnants of six teeth. QM F18827 (proposed neotype), articulated skull and mandible (Fig. 4B) with asso- ciated cervical and pectoral vertebrae, components of the pectoral girdle and proximal end of the humerus (see McHenry 2009, pp. 180–185).
Type locality, unit and age
QM F1609 was derived from an unspecified locality in the Hughenden region of central-northern Queensland, Australia (Longman 1924). Longman (1930, p. 1) also attributed two incomplete propodials (QM F2137) and some weathered bone fragments (apparently occurring together with a caudal verte- bral series: Romer & Lewis 1959) from a locality 'two miles [$3.2km] south of Hughenden'. QM F18827 was recovered
AUSTRALIAN MESOZOIC TETRAPODS
'from the airstrip on Lucerne Station, [$9 km] north of Richmond' (McHenry 2009, p. 180). McHenry (2009) identified the type unit as the Toolebuc Formation in the Wilgunya Subgroup of the Rolling Downs Group (Eromanga Basin); cor- related with the upper Albian (Lower Cretaceous) Canningopsis denticulata and lower Endoceratium ludbrookae dinocyst zones (sensu Partridge 2006) by Foley et al. (2022).
Remarks
Despite early reports of 'comprehensive undescribed mater- ial' being available for study at the QM (Persson 1960, p. 4), Welles (1962, p. 48) designated Kronosaurus queenslandicus a nomen vanum (1⁄4 name designated on fragmentary type remains: Mones 1989), and recommended establishment of a neotype based on the 'material at Harvard University' (presumably referring to the incomplete skull and skeleton MCZ 1285: White 1935, Anonymous 1959, Fletcher 1959, Romer & Lewis 1959). Persson (1960, p. 4) likewise refrained from documenting the QM specimens 'before a description of the Harvard skeleton has been published'. Nevertheless, White (1935) and Romer & Lewis (1959) had already described MCZ 1285 and a second premaxillary ros- trum with associated symphyseal section of the mandible (MCZ 1284: see White 1935) in some detail.
Clearly, these initial first-hand examinations (e.g., Longman 1924, 1930, White 1935, Romer & Lewis 1959) and subsequent reviews (e.g., Persson 1960, Welles 1962) assumed a conspecific assignment of the then accessioned QM and MCZ fossils. However, Molnar (1982, 1991, p. 633) reiterated that 'K. queenslandicus is based on very incom- plete material' (QM F1609), and although '[more] complete specimens of probable K. queenslandicus' had been collected by the QM, 'no attempt at adequate comparison with the type material [had] yet been carried out'. Moreover, Molnar (1982, p. 186, 1991, p. 633) noted that the 'Harvard krono- saur' (MCZ 1285) was excavated from an upper Aptian deposit of the Doncaster Member in the Wallumbilla Formation (Wilgunya Subgroup) north of Richmond, whereas QM F1609 and a 'second partial skull (QM F24446 [sic QM F2446])' were both derived from the upper Albian Toolebuc Formation near Hughenden. QM F2446 was reportedly 'very broad, low, and flat (at least 87cm across by only 13cm high), with large upwardly directed orbits' (see Molnar 1991, p. 632, fig. 15), whereas the 'Harvard skull (MCZ 1285) seems deeper' (Molnar 1982, p. 186, Molnar 1991, p. 633). As acknowledged by Molnar (1991, p. 633), though, '[t]he Harvard skeleton is less complete than appears from the mount'. Indeed, White (1935, p. 220) explicitly stated that the extensively restored skull of MCZ 1285 included only 'the brain case with left quadrate attached and the posterior end of the lower jaw, a section of the face containing the anterior border of the left orbit and left external naris, a portion of the rostrum showing the maxillary-premaxillary suture, and a portion of the man- dibular symphysis showing the division of the two rami'. Its original cranial proportions are, therefore, uncertain. Furthermore, the long-awaited comprehensive inspection of K. queenslandicus remains from QM and MCZ by McHenry (2009, p. 427) found 'no evidence that more than one taxon of large pliosaur is present in the Toolebuc fauna ... , and that [all of] this material can be confidently assigned to Kronosaurus queenslandicus Longman'. McHenry (2009, p. 429) continued with 'the Doncaster material [MCZ 1284, MCZ 1285] is referrable to Kronosaurus' because the
'premaxillae bear four teeth', which McHenry (2009) consid- ered diagnostic. The differences in cranial proportions men- tioned by Molnar (1991) were also 'undoubtedly a result of taphonomy' (McHenry 2009, p. 430). Finally, 'assignment of the Doncaster [Member] Kronosaurus specimens to Kronosaurus queenslandicus [was] maintained, pending the results of future examination, as this taxonomy reflects the most parsimonious interpretation of the available data' (McHenry 2009, p. 431). We concur with these findings, which have since been reinforced by studies attributing other morphologically consistent specimens from strati- graphically proximal Rolling Downs Group strata of the upper Aptian Bulldog Shale (Marree Subgroup), upper Aptian Doncaster Member of the Wallumbilla Formation in New South Wales, and the upper Albian Allaru Mudstone (e.g., Kear 2005b, 2006a, Holland 2018).
Regardless, No␘e & Gom␙ez-P␙erez (2022, p. 6) examined a painted plaster cast of QM F1609 (MCZ 2445) and posited that '[in] the absence of diagnostic features of the holotype, the genus Kronosaurus and the type species Kronosaurus queenslandicus cannot be satisfactorily diagnosed or com- pared to other pliosaurid material. To date, as no diagnostic neotype has been formally designated (as proposed by Welles 1962; Molnar [1982]; McHenry 2009), the taxonomic name (genus, and nominotypical and only species), Kronosaurus queenslandicus, must be restricted to the holo- type specimen QM F1609, which should be considered Pliosauridae (?Brauchauchiniinae [sic Brachaucheninae]) indet.' This patently ignored McHenry's (2009, p. 257) unambiguous recognition that 'there is no indication of more than one taxon of large pliosaur from the Toolebuc Formation, [therefore] the holotype can be assumed to rep- resent the same species as the more complete specimens ... [in] particular, QM F18827 preserves all of the features— premaxillary tooth count, mandibular symphysis, tooth shape and ornamentation, anisodonty of the tooth row, ver- tebral centra morphology—that can separate the Toolebuc Formation large pliosaur taxon from all other currently described species of pliosaur'. A second specimen of K. queenslandicus from the Toolebuc Formation comprising an articulated postcranial skeleton (QM F10113) was also nomi- nated to distinguish K. queenslandicus from the apparently closely related taxon Monquirasaurus boyacensis (Hampe, 2002), which was referred to Kronosaurus by Hampe (1992). Consequently, we again support McHenry's (2009, p. 257) conclusion that '[either] of these two specimens may be appropriate candidates for the name-bearing specimen for Kronosaurus queenslandicus. Under the International Committee of Zoological Nomenclature (ICZN) rules, re- allocation of the type specimen for a species, on the grounds that the holotype has not been lost or destroyed, but is non- diagnostic, requires a petition to the ICZN committee. It is recommended that this action be taken in order to retain Kronosaurus queenslandicus Longman 1924 as a valid spe- cies'. Accordingly, we reject the suggestion of No␘e & Go␙mez-P␙erez (2022, p. 6) that because 'only a single genus (and possibly species) of giant sized pliosaurid [is evident in the] Australian Aptian–Albian deposits (McHenry 2009) ... all material previously assigned to Kronosaurus or Kronosaurus queenslandicus [should be provisionally assigned to a] new genus'. In our opinion, this creates unwarranted taxonomic instability via merger of Kronosaurus and potentially K. queenslandicus with obvious junior synonyms. Moreover, No␘e & Go␙mez-P␙erez (2022)
listed (but did not redescribe) MCZ 1285 as a replacement holotype, which is inadequate since it comprises a notori- ously inaccurate plaster reconstruction (McHenry 2009) incorporating severely weathered and incomplete embedded fossil components (see Romer & Lewis 1959). The extent of restoration has even instigated a popular nickname, 'Plasterosaurus', and calls for disassembly and CT scanning of MCZ 1285 to detect any taxonomically informative ori- ginal bone material (see Tembe & Siddiqui 2014, p. 55). In the interim, we adhere to the diagnoses of McHenry (2009) and others (e.g., Holland 2018), which justifiably classified the stratigraphically conformable upper Albian Toolebuc Formation and Allaru Mudstone brachauchenine fossils as K. queenslandicus, with QM F18827 representing the most feasible neotype pending a detailed redescription and formal nomenclatural ruling by the ICZN.
Eiectus No␘e & Gom␙ez-P␙erez, 2022 Type species
Eiectus longmani No␘e & Gom␙ez-P␙erez, 2022. Eiectus longmani No␘e & Gom␙ez-P␙erez, 2022
1991, Kronosaurus sp. Molnar, p. 613.
1993, ?Kronosaurus sp. Thulborn & Turner, p. 491. 2022, Eiectus longmani No␘e & Gom␙ez-P␙erez, p. 6.
Holotype
MCZ 1285, an incomplete skull, mandible and postcranial skeleton embedded within a reconstructed plaster exhibition mount (Fig. 4A).
Type locality, unit and age
MCZ 1285 was reportedly excavated in the vicinity of Army Downs bore 'five miles [$8km] further north' of another referred specimen, MCZ 1284, which was recovered '30 miles [$48 km] to the north of Richmond' in central-north- ern Queensland, Australia (Romer & Lewis 1959, p. 1). Based on this locality information, the source unit has been interpreted as the Doncaster Member of the Wallumbilla Formation in the Wilgunya Subgroup of the Rolling Downs Group (Eromanga Basin); correlated with the upper Aptian (Lower Cretaceous) Muderongia australis and lower Odontochitina operculata dinocyst zones (sensu Partridge 2006) by Foley et al. (2022).
Remarks
No␘e & Gom␙ez-P␙erez (2022, p. 6) erected Eiectus longmani to accommodate 'all material previously assigned to Kronosaurus or Kronosaurus queenslandicus'. However, because this prioritizes a junior synonym based on a recon- structed display mount manifesting unconfirmable diagnos- tic character states, we restrict E. longmani to define only MCZ 1285 and MCZ 1284 until a more rigorous evaluation is carried out. This acknowledges the unresolved possibility of taxonomic distinction from the upper Albian Toolebuc Formation/Allaru Mudstone K. queenslandicus as diagnosed by McHenry (2009) using the holotype QM F1609, proposed neotype QM F18827, and referred specimen QM F10113 (see also Holland [2018] for a differential diagnosis).