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Case 3815 – Tyrannosauridae Osborn, 1906 (Dinosauria, Theropoda): proposed conservation by reversal of precedence with Deinodontidae Cope, 1866 and Dryptosauridae Marsh, 1890



The purpose of this application, under Article 23.9.3 of the Code, is to conserve at both the family and superfamily level the widely used family-group name TYRANNOSAURIDAE (-OIDEA) Osborn, 1906 (Dinosauria, Theropoda), which is threatened by its senior subjective synonyms DEINODONTIDAE (-OIDEA) Cope, 1866 and DRYPTOSAURIDAE (-OIDEA) Marsh, 1890. Strict application of the Code would result in unnecessary confusion in dinosaur taxonomy since the names TYRANNOSAURIDAE and TYRANNOSAUROIDEA have been used consistently in the vertebrate paleontological literature since the 1970s with only a very few exceptions.
29Bulletin of Zoological Nomenclature 77 (30 April 2020) ISSN 2057-0570 (online)
Case 3815 – Tyrannosauridae Osborn, 1906 (Dinosauria,
Theropoda): proposed conservation by reversal of precedence with
deinodonTidae Cope, 1866 and drypTosauridae Marsh, 1890
Chan-gyu Yun
Vertebrate Paleontological Institute of Incheon, Incheon 21974, Republic of
Korea / Biological Sciences, Inha University, Incheon 22212, Republic of Korea
Abstract. The purpose of this application, under Article 23.9.3 of the Code, is to
conserve at both the family and superfamily level the widely used family-group name
Tyrannosauridae (-oidea) Osborn, 1906 (Dinosauria, Theropoda), which is threatened by
its senior subjective synonyms deinodonTidae (-oidea) Cope, 1866 and drypTosauridae
(-oidea) Marsh, 1890. Strict application of the Code would result in unnecessary confusion
in dinosaur taxonomy since the names Tyrannosauridae and Tyrannosauroidea have
been used consistently in the vertebrate paleontological literature since the 1970s with
only a very few exceptions.
Keywords. Nomenclature; taxonomy; Dinosauria; Theropoda; Tyrannosauroidea;
Tyrannosauridae; deinodonToidea; deinodonTidae; drypTosauroidea; drypTosauridae.
1. In 1855, Ferdinand Vandeveer Hayden collected several large theropod teeth
from the Upper Cretaceous Judith River Formation in Montana, and Leidy (1856: 72)
erected Deinodon horridus Leidy, 1856 based on them. Cope (1866: 279) coined the
family-level name dinodonTidae Cope, 1866 for this genus (which he incorrectly spelled
as Dinodon) and species, and Brown (1914: 377) justiably emended it (see Articles
32.5.3 and 35.4.1 of the Code) to deinodonTidae Cope, 1866. Originally, Cope (1866)
included Deinodon and Laelaps Cope, 1866 (the latter preoccupied by Laelaps Koch,
1836, currently Dryptosaurus Marsh, 1877, type species Dryptosaurus aquilunguis
(Cope, 1877)) in this family, and Matthew & Brown (1922) considered Deinodon,
Dryptosaurus, Gorgosaurus Lambe, 1914, Albertosaurus Osborn, 1905, Tyrannosaurus
Osborn, 1905 and Dynamosaurus Osborn, 1905 as deinodontids. Until the 1970s, the name
deinodonTidae was applied to the theropod dinosaurs now known as Tyrannosauridae
Osborn, 1906. The concepts are nearly identical and both names have been considered to
be subjective synonyms of each other (e.g., Russell, 1970; Holtz, 2004).
2. Today, Deinodon horridus is regarded as a nomen dubium that possibly represents
teeth shed from contemporaneous Gorgosaurus libratus Lambe, 1914 (e.g., Russell, 1970).
However, separating the isolated teeth of G. libratus from those of the contemporaneous
Bulletin of Zoological Nomenclature 77 (30 April 2020) ISSN 2057-0570 (online)30
tyrannosaurine Daspletosaurus torosus Russell, 1970 is nearly impossible because
they are very similar in morphology (Buckley et al., 2010) and because the denticle
density ranges of teeth of the two genera overlap (Carr & Williamson, 2000). Generally,
tyrannosaurid (= deinodontid) teeth, including the type specimens of Deinodon horridus,
are morphologically uniform in having labiolingually expanded basal parts and carinae
that are offset from the mesial and distal edges (e.g., Holtz, 2004). Although Deinodon
horridus may be referable to this family, e.g. as Tyrannosauridae incertae sedis, its
teeth have no distinctive features that allow it to be referred to either of the currently
recognized subfamilies, Tyrannosaurinae Osborn, 1906 or alberTosaurinae Currie,
Hurum & Sabath, 2003. If it were referred to either, DeinodonTinae Cope, 1866 would
become the valid name of the subfamily involved.
3. Marsh (1890: 424) erected the family-group taxon drypTosauridae Marsh, 1890
to encompass Dryptosaurus along with other North American theropods. However, the
highly fragmentary nature of the holotype of Dryptosaurus aquilunguis has made its
classication highly controversial (e.g., Carpenter et al., 1997; Brusatte et al., 2011).
The name drypTosauridae was last used by Carpenter et al. (1997) as those authors
were uncertain about the evolutionary relationships of Dryptosaurus with other theropods
and treated the family as monotypic. Otherwise, a close afnity of Dryptosaurus with
deinodontids (= tyrannosaurids) has been accepted since the late 1800s (e.g., Cope, 1866;
Brown, 1914; Matthew & Brown, 1922). Most recent phylogenetic studies, as well as a
redescription of the holotype of the type species Dryptosaurus aquilunguis, have placed
Dryptosaurus as a basal coelurosaurian theropod nested deep within Tyrannosauroidea
Osborn, 1906 (e.g., Holtz, 2004; Carr et al., 2005; Carr & Williamson, 2010; Brusatte
et al., 2010; Loewen et al., 2013; Brusatte & Carr, 2016; Carr et al., 2017), and none of
these works has used the family name drypTosauridae as taxonomically valid.
4. Osborn (1906: 283) coined the family name Tyrannosauridae Osborn, 1906 for
Tyrannosaurus Osborn, 1905, and this name is now used to encompass large, basal,
hypercarnivorous coelurosaurs such as Gorgosaurus libratus, Albertosaurus sarcophagus
Osborn, 1905 and Tyrannosaurus rex Osborn, 1905. Walker (1964) proposed to use a
superfamily Tyrannosauroidea to group Tyrannosauridae with several pseudosuchians
and spinosauridae Stromer, 1915, but this treatment was not supported by subsequent
authors. Although Tyrannosauroidea and its subgroup Tyrannosauridae were considered
as carnosaurs for many decades (e.g., Osborn, 1906; Walker, 1964; Russell, 1970), they
are now treated as either the basal-most coelurosaurs or as being grouped among other
basal coelurosaurs at a level more derived than CompsognaThidae Cope, 1871 (e.g., Holtz,
2004; Loewen et al., 2013; Brusatte & Carr, 2016; Yun, 2016). While many works before
the 1970s used deinodonTidae instead of Tyrannosauridae (e.g., Brown, 1914; Matthew
& Brown, 1922; Gilmore, 1946; Maleev, 1955), most modern authors (e.g., Olshevsky,
1991; Carpenter, 1992; Holtz, 1994, 1996, 2000, 2001, 2004, 2012; Carpenter et al.,
1997; Padian et al., 1999; Sereno, 1999; Carr & Williamson, 2000, 2010; Currie, 2003;
Currie et al., 2003; Carr et al., 2005, 2017; Sereno et al., 2005, 2009; Sereno & Brusatte,
2009; Brusatte et al., 2010, 2011, 2012, 2014, 2016; Buckley et al., 2010; Brusatte &
Benson, 2013; Loewen et al., 2013; Hendrickx et al., 2015; Brusatte & Carr, 2016; Yun,
2016, 2017; Cau, 2018; Nesbitt et al., 2019) have followed Russell (1970) in preferring
Tyrannosauridae on the grounds that Deinodon horridus is a nomen dubium with type
specimens that are not referable to any genus- or species-group taxon.
5. Nothing in the current Code (ICZN, 1999) implies the invalidation of a family-
31Bulletin of Zoological Nomenclature 77 (30 April 2020) ISSN 2057-0570 (online)
group name when the taxonomic validity of its type genus is dubious. Olshevsky (1991)
rst recognized this, but he preferred to use Tyrannosauridae because deinodonTidae had
rst appeared as an emendation of dinodonTidae in Brown (1914) and thus seemed to him
to be junior to Tyrannosauridae proposed in 1906. He was incorrect, as Article 32.2.2 of
the Code requires a justied emendation to take the authorship and date of the original
publication, i.e. Cope, 1866. Additionally, according to Article 36, “a name established
for a taxon at any rank in the family group is deemed to have been simultaneously
established for nominal taxa at all other ranks in the family group”. Therefore, just as
deinodonTidae has priority over Tyrannosauridae, so do deinodonToidea Cope, 1866
and drypTosauroidea Marsh, 1890 have priority over Tyrannosauroidea Osborn, 1906.
6. Both deinodonTidae and drypTosauridae were proposed before 1899, but they
were commonly used in pre-1970s literature and even more recently (e.g., Carpenter et
al., 1997; Martyniuk, 2012). The present case cannot be resolved by invoking prevailing
usage under Art. 23.9.1 because the requirements of Art. are not met. Insisting
on a reversion of Tyrannosauridae to deinodonTidae (or drypTosauridae) would create
unnecessary confusion in taxonomy since Tyrannosauridae has been used in the vast
majority of theropod phylogenetic and taxonomic studies during the past half-century.
The same applies to Tyrannosauroidea. In the interest of nomenclatural stability, it
seems necessary to invoke Article 23.9.3 of the Code and ask the Commission to use its
plenary power to conserve the widely used family name Tyrannosauridae Osborn, 1906
by reversal of precedence with deinodonTidae Cope, 1866 and drypTosauridae Marsh,
7. The International Commission on Zoological Nomenclature is accordingly asked:
(1) to use its plenary power to rule:
(a) that the family-group name Tyrannosauridae Osborn, 1906 is to be
given precedence over deinodonTidae Cope, 1866 whenever the two are
considered to be synonyms;
(b) that the family-group name Tyrannosauridae Osborn, 1906 is to be
given precedence over drypTosauridae Marsh, 1890 whenever the two
are considered to be synonyms;
(2) to place on the Ofcial List of Family-Group Names in Zoology the following
(a) Tyrannosauridae Osborn, 1906, type genus: Tyrannosaurus Osborn,
1905 (Theropoda) with the endorsement that it is to be given precedence
over deinodonTidae Cope, 1866 and drypTosauridae Marsh, 1890,
whenever the rst is considered to be a synonym of either of the last
two, as ruled in (1) above;
(b) deinodonTidae Cope, 1866, type genus: Deinodon Leidy, 1856
(Theropoda) with the endorsement that it is not to be given priority over
Tyrannosauridae Osborn, 1906 whenever the two are considered to be
synonyms, as ruled in (1)(a) above; and
(c) drypTosauridae Marsh, 1890, type genus: Dryptosaurus Marsh 1877
(Theropoda) with the endorsement that it is not to be given priority over
Tyrannosauridae Osborn, 1906 whenever the two are considered to be
synonyms, as ruled in (1)(b) above.
Bulletin of Zoological Nomenclature 77 (30 April 2020) ISSN 2057-0570 (online)32
The author thanks the ICZN secretary Gwynne Lim, the Editor Neal L. Evenhuis, and
two anonymous reviewers for their comments and valuable discussions. Special thanks
go to Yeon-Woo Lee, Bong-Hwan Ji, Dong-Yoon Lee, Dong-Geun Lee, Ha-Jun Lee,
Hyo-Jin Ji, Yeon-Sung Kim and Ga-Hee Kim for their support and care.
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Acknowledgement of receipt of this application was published in BZN 76: 166.
Comments on this case are invited for publication (subject to editing) in the Bulletin; they should
be sent to the Secretariat, International Commission on Zoological Nomenclature, c/o Lee Kong
Chian Natural History Museum, 2 Conservatory Drive, Singapore 117377, Republic of Singapore
ResearchGate has not been able to resolve any citations for this publication.
Full-text available
Late Cretaceous dinosaur assemblages of North America—characterized by gigantic tyrannosaurid predators, and large-bodied herbivorous ceratopsids and hadrosaurids—were highly successful from around 80 million years ago (Ma) until the end of the ‘Age of Dinosaurs’ 66 Ma. However, the origin of these iconic faunas remains poorly understood because of a large, global sampling gap in the mid-Cretaceous, associated with an extreme sea-level rise. We describe the most complete skeleton of a predatory dinosaur from this gap, which belongs to a new tyrannosauroid theropod from the Middle Turonian (~92 Ma) of southern Laramidia (western North America). This taxon, Suskityrannus hazelae gen. et sp. nov., is a small-bodied species phylogenetically intermediate between the oldest, smallest tyrannosauroids and the gigantic, last-surviving tyrannosaurids. The species already possesses many key features of the tyrannosaurid bauplan, including the phylogenetically earliest record of an arctometatarsalian foot in tyrannosauroids, indicating that the group developed enhanced cursorial abilities at a small body size. Suskityrannus is part of a transitional Moreno Hill (that is, Zuni) dinosaur assemblage that includes dinosaur groups that became rare or were completely absent in North America around the final 15 Myr of the North American Cretaceous before the end-Cretaceous mass extinction, as well as small-bodied forebears of the large-bodied clades that dominated at this time.
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Birds are one of the most successful groups of vertebrates. The origin of birds from their reptilian ancestors is traditionally rooted near the Jurassic "Urvogel" Archaeopteryx, an approach that has contributed in defining the dichotomy between the "reptilian" (pre-Archaeopteryx) and "avian" (post-Archaeopteryx) phases of what is instead a single evolutionary continuum. A great and still ever increasing amount of evidence from the fossil record has filled the gaps between extinct dinosaurs, Mesozoic birds and modern avians, and led to the revision of the misleading dichotomy between pre-and post-Archaeopteryx stages in the evolution of bird biology. Herein, the progressive assembly of the modern avian body plan from the archosaurian ancestral condition is reviewed using a combination of phylogenetic methods. 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It is an undoubtable fact that Tyrannosaurus rex is the most iconic dinosaur species of all time. However, it is currently debatable whether this species has a North American origin or Asian origin. In this paper, I test these two hypotheses based on current fossil records and former phylogenetic analyses. Phylogenetic and fossil evidence, such as derived tyrannosaurine fossils of Asia, suggests that the hypothesis of an Asian origin of Tyrannosaurus rex is the most plausible one, but this is yet to be certain due to the scarcity of fossil records.
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A new species of tyrannosaurid from the upper Two Medicine Formation of Montana supports the presence of a Laramidian anagenetic (ancestor-descendant) lineage of Late Cretaceous tyrannosaurids. In concert with other anagenetic lineages of dinosaurs from the same time and place, this suggests that anagenesis could have been a widespread mechanism generating species diversity amongst dinosaurs, and perhaps beyond. We studied the excellent fossil record of the tyrannosaurid to test that hypothesis. Phylogenetic analysis places this new taxon as the sister species to Daspletosaurus torosus. However, given their close phylogenetic relationship, geographic proximity, and temporal succession, where D. torosus (~76.7?75.2 Ma) precedes the younger new species (~75.1?74.4 Ma), we argue that the two forms most likely represent a single anagenetic lineage. Daspletosaurus was an important apex predator in the late Campanian dinosaur faunas of Laramidia; its absence from later units indicates it was extinct before Tyrannosaurus rex dispersed into Laramidia from Asia. In addition to its evolutionary implications, the texture of the facial bones of the new taxon, and other derived tyrannosauroids, indicates a scaly integument with high tactile sensitivity. Most significantly, the lower jaw shows evidence for neurovasculature that is also seen in birds.
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The theropod family Tyrannosauridae (Dinosauria) is composed of four genera and seven species. All taxa are known from nearly complete skeletons and/ or skulls, thus making it one of the best documented large theropod families. The stratigraphic and palaeobiogeographic distribution of the Tyrannosauridae extends from the lower Campanian to upper Maastrichtian of North America, and to the Campanian-Maastrichtian of Asia.
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The well supported clade Tyrannosauroidea represents one of the most basal coelurosaurian theropods. Given that current fossil records of earliest coelurosaur theropods are extremely scarce, basal-most tyrannosauroid materials are key to understanding the origin and diversification of coelurosaurs. Here, I present a brief overview of currently known basal tyrannosauroids of Jurassic age, discussing their systematics and distribution. The currently oldest known Jurassic tyrannosauroids are from Europe continent, possibly suggesting the European origin of the superfamily.
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Tyrannosaurids-the familiar group of carnivorous dinosaurs including Tyrannosaurus and Albertosaurus-were the apex predators in continental ecosystems in Asia and North America during the latest Cretaceous (ca. 80-66 million years ago). Their colossal sizes and keen senses are considered key to their evolutionary and ecological success, but little is known about how these features developed as tyrannosaurids evolved from smaller basal tyrannosauroids that first appeared in the fossil record in the Middle Jurassic (ca. 170 million years ago). This is largely because of a frustrating 20+ million-year gap in the mid-Cretaceous fossil record, when tyrannosauroids transitioned from small-bodied hunters to gigantic apex predators but from which no diagnostic specimens are known. We describe the first distinct tyrannosauroid species from this gap, based on a highly derived braincase and a variety of other skeletal elements from the Turonian (ca. 90-92 million years ago) of Uzbekistan. This taxon is phylogenetically intermediate between the oldest basal tyrannosauroids and the latest Cretaceous forms. It had yet to develop the giant size and extensive cranial pneumaticity of T. rex and kin but does possess the highly derived brain and inner ear characteristic of the latest Cretaceous species. Tyrannosauroids apparently developed huge size rapidly during the latest Cretaceous, and their success in the top predator role may have been enabled by their brain and keen senses that first evolved at smaller body size.
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Tyrannosauroids—the group of carnivores including Tyrannosaurs rex—are some of the most familiar dinosaurs of all. A surge of recent discoveries has helped clarify some aspects of their evolution, but competing phylogenetic hypotheses raise questions about their relationships, biogeography, and fossil record quality. We present a new phylogenetic dataset, which merges published datasets and incorporates recently discovered taxa. We analyze it with parsimony and, for the first time for a tyrannosauroid dataset, Bayesian techniques. The parsimony and Bayesian results are highly congruent, and provide a framework for interpreting the biogeography and evolutionary history of tyrannosauroids. Our phylogenies illustrate that the body plan of the colossal species evolved piecemeal, imply no clear division between northern and southern species in western North America as had been argued, and suggest that T. rex may have been an Asian migrant to North America. Over-reliance on cranial shape characters may explain why published parsimony studies have diverged and filling three major gaps in the fossil record holds the most promise for future work.