Taxonomic Status of Nanotyrannus lancensis (Dinosauria: Tyrannosauroidea)—A Distinct Taxon of Small-Bodied Tyrannosaur

Fossil Studies, Год журнала: 2024, Номер 2(1), С. 1 - 65

Опубликована: Янв. 3, 2024

Tyrannosaurs are among the most intensively studied and best-known dinosaurs. Despite this, their relationships systematics highly controversial. An ongoing debate concerns validity of Nanotyrannus lancensis, interpreted either as a distinct genus small-bodied tyrannosaur or juvenile Tyrannosaurus rex. We examine multiple lines evidence show that strongly supports recognition species for following reasons: 1. High diversity tyrannosaurs predatory dinosaurs idea tyrannosaurids inhabited late Maastrichtian Laramidia; 2. lacks characters supporting referral to Tyrannosaurinae but differs from T. rex in >150 morphological characters, while intermediate forms combining features unknown; 3. Histology shows specimens showing (i) skeletal fusions, (ii) mature skull bone textures, (iii) slow growth rates relative rex, (iv) decelerating final years life, (v) curves predicting adult masses ~1500 kg less, these animals subadults young adults, not Tyrannosaurus; 4. series other tyrannosaurids, including Tarbosaurus Gorgosaurus, do changes proposed Nanotyrannus–Tyrannosaurus series, deriving requires several inconsistent with known patterns dinosaur development; 5. Juvenile exist, diagnostic 6. Phylogenetic analysis suggests may lie outside Tyrannosauridae. Tyrannosaur before K-Pg extinction is higher than previously appreciated. The challenges inherent diagnosing based on fossils mean paleontologists be systematically underestimating ancient ecosystems.

Язык: Английский

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A giant tyrannosaur from the Campanian–Maastrichtian of southern North America and the evolution of tyrannosaurid gigantism

Scientific Reports, Год журнала: 2024, Номер 14(1)

Опубликована: Янв. 11, 2024

Abstract Tyrannosaurid dinosaurs dominated as predators in the Late Cretaceous of Laurasia, culminating evolution giant Tyrannosaurus rex , both last and largest tyrannosaurid. Where when Tyrannosaurini ( T. kin) originated remains unclear. Competing hypotheses place tyrannosaurin origins Asia, or western North America (Laramidia). We report a new tyrannosaurin, mcraeensis from Campanian–Maastrichtian Hall Lake Formation New Mexico, based on fossil previously referred to . predates by ~ 6–7 million years, yet rivaled it size. Phylogenetic analysis recovers sister suggests southern Laramidia. Evolution tyrannosaurs America, alongside ceratopsians, hadrosaurs, titanosaurs large-bodied evolved at low latitudes America.

Язык: Английский

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A New Tyrant Dinosaur from the Late Campanian of Mexico Reveals a Tribe of Southern Tyrannosaurs

Fossil Studies, Год журнала: 2024, Номер 2(4), С. 245 - 272

Опубликована: Сен. 25, 2024

The end of the Cretaceous saw Western Interior Seaway divide North America into two land masses, Laramidia in west and Appalachia east. Laramidian dinosaurs inhabited a narrow strip extending from Mexico to Alaska. Within this geographically restricted area, evolved high diversity endemism, with distinct species north south. Here, we report new tyrannosaurid Late Campanian-aged Cerro del Pueblo Formation Coahuila, Mexico, which is part tribe tyrannosaurs originating southern Laramidia. Phylogenetic analysis recovers tyrannosaur as clade including Labocania anomala La Bocana Roja Baja California Norte, Bistahieversor sealeyi Kirtland New Teratophoneus curriei Kaiparowits Utah, Dynamoterror dynastes Menefee Mexico. Distinct frontal morphology younger age (~72.5–73 Ma versus >75.8 for L. anomala) support recognition Labocania, aguillonae. dominated at time when was by daspletosaurins albertosaurines. endemism seen tyrannosaurids remarkable, given that modern apex predators have large geographic ranges hints carnivorous has been underestimated.

Язык: Английский

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A transitional species of Daspletosaurus Russell, 1970 from the Judith River Formation of eastern Montana

PeerJ, Год журнала: 2022, Номер 10, С. e14461 - e14461

Опубликована: Ноя. 25, 2022

Here we describe a new derived tyrannosaurine, Daspletosaurus wilsoni sp. nov., from Judithian strata (~76.5 Ma) intermediate in age between either of the previously described species this genus. D. displays unique combination ancestral and characteristics, including cornual process lacrimal reduced height relative to torosus more basal tyrannosaurines, prefrontal with long axis oriented rostrally than horneri tyrannosaurines. The description taxon provides insight into evolutionary mode Tyrannosaurinae, lending strength previous hypotheses anagenesis within increasing resolution which evolution lineage can be reconstructed. Cladistic phylogenetic methods, stratigraphy, qualitative analysis morphology relevant taxa supports an anagenetic model for origin morphological novelty genus, highlighting predominance among contemporary dinosaur lineages.

Язык: Английский

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Taphonomic and Diagenetic Pathways to Protein Preservation, Part II: The Case of Brachylophosaurus canadensis Specimen MOR 2598

Biology, Год журнала: 2022, Номер 11(8), С. 1177 - 1177

Опубликована: Авг. 5, 2022

Recent recoveries of peptide sequences from two Cretaceous dinosaur bones require paleontologists to rethink traditional notions about how fossilization occurs. As part this shifting paradigm, several research groups have recently begun attempting characterize biomolecular decay and stabilization pathways in diverse paleoenvironmental diagenetic settings. To advance these efforts, we assessed the taphonomic geochemical history Brachylophosaurus canadensis specimen MOR 2598, left femur which was previously found retain endogenous cells, tissues, structural proteins. Combined stratigraphic trace element data show that after brief fluvial transport, articulated hind limb buried a sandy, likely-brackish, estuarine channel. During early diagenesis, percolating groundwaters stagnated within bones, forming reducing internal microenvironments. exposure weathering also caused surficial leaching elements specimen. Despite redox regimes, proteins were able survive through attesting their remarkable resiliency over geologic time. Synthesizing our findings with other recent studies reveals oxidizing conditions initial ~48 h postmortem likely promote molecular reactions retention early-diagenetic signatures may be useful proxy for recovery potential.

Язык: Английский

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Resolving the "Ontogeny Problem" in Vertebrate Paleontology

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2024, Номер unknown

Опубликована: Окт. 28, 2024

Abstract Ontogenetic change is a major source of phenotypic variation among members species and often greater magnitude than the anatomical differences that distinguish closely related species. Ontogeny has therefore become problematic confounding variable in vertebrate paleontology, especially study systems distant from extant crown clades, rendering taxonomic hypothesis testing (a fundamental process evolutionary biology) rife with difficulty. Paleontologists have adopted quantitative methods to compensate for perception juvenile specimens lack diagnostic apomorphies seen their adult conspecifics. Here, I critically evaluate these assumptions guide interpretation using µCT dataset comprising growth series American Chinese alligator. find several widespread are scientifically unjustifiable, two popular – geometric morphometrics cladistic analysis ontogeny unacceptably high rates type II error present numerous procedural difficulties. However, also identify suite ontogenetically invariant characters differentiate living Alligator throughout ontogeny. These overwhelmingly correspond develop prior (and play signaling role in) development cranial skeleton itself, suggesting ontogenetic invariance consequence widely conserved developmental program. observations suggest architecture cranium fixed early embryonic development, remodeling does not alter topological relationships bones or soft tissue structures they house. propose general model future tests fossil record, which different stages single can be falsified by discovery character cannot attributed plausibly variation.

Язык: Английский

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Taxonomic status of Nanotyrannus lancensis (Dinosauria: Tyrannosauroidea) — a distinct taxon of small-bodied tyrannosaur

Опубликована: Окт. 23, 2023

Abstract: Tyrannosaurs, giant predatory dinosaurs from the end of Cretaceous, are among most intensively researched and best-known groups dinosaurs. Despite this, their relationships systematics highly controversial, number tyrannosaur species occurring in latest Cretaceous North America is debated. An ongoing debate concerns status Nanotyrannus lancensis, which has variously been interpreted as a distinct taxon small-bodied or juvenile coeval Tyrannosaurus rex. Here, we review multiple lines evidence show that totality strongly supports recognition species: 1. The high diversity Late tyrannosaurs general consistent with idea more than one lived late Maastrichtian Western America; 2. shows few if any diagnostic characters allowing referral specifically to even Tyrannosaurinae, but differentiated T. rex by at least 77 morphological characters, while intermediate forms, combining characteristics rex, remain unknown; 3. Histological individuals previously referred lancensis (i) skeletal fusions maturity, (ii) skull bone textures (iii) slow growth rates relative (iv) decelerating final years life, (v) curves predicting adult body sizes ~1500 kg less, implying these animals young adults, not juveniles Tyrannosaurus; 4. Juveniles other tyrannosaurids, including Gorgosaurus Tarbosaurus, do kinds changes proposed for Nanotyrannus-Tyrannosaurus series, suggesting morphology cannot simply be explained result immaturity; 5. Small exist, comparable size Nanotyrannus, exhibit features Tyrannosaurus, differ Nanotyrannus; 6. Phylogenetic analysis suggests tyrannosaurid. Taken together, rejects tentatively placement outside Tyrannosauridae non-tyrannosaurid member Tyrannosauroidea. Tyrannosaur appears have higher appreciated before K-Pg extinction. difficulties recognizing based on fossils alone mean paleontologists may systematically biased towards underestimating ancient ecosystems.

Язык: Английский

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Enduring senses

Synthese, Год журнала: 2022, Номер 200(4)

Опубликована: Июль 8, 2022

Abstract The meanings of words seem to change over time. But while there is a growing body literature in linguistics and philosophy about meaning change, has been little discussion the metaphysical underpinnings change. central aim this paper push forward by surveying terrain advocating for particular picture. In so doing, we hope clarify various aspects nature as well prompt future philosophical investigation into topic. More specifically, two parts. first, broadly exploratory, part surveys accounts goal here lay out terrain, thereby highlighting some key choice points. Then, second part, after critiquing Prosser’s (Philosophy Phenomenol Res 100(3):657–676, 2020) exdurantism ‘mental files’, sketch defend enduring senses view

Язык: Английский

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CLADISTICS ruined my life: intersections of fandom, internet memes, and public engagement with science

Journal of Science Communication, Год журнала: 2022, Номер 21(05), С. Y01 - Y01

Опубликована: Июль 25, 2022

In an increasingly mediated culture, social institutions such as science, public health, and civic engagement exist within the same modes of discourse popular media. As a human endeavor, science is also cultural phenomenon, there are webs multidirectional layered communication that occur between formal communication, pop and, indeed, For participants, with entertainment may be one in same. This essay draws from research transformative works, fan studies, memetics to examine how engages media digital cultures.

Язык: Английский

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Observations on Paleospecies Determination, With Additional Data on Tyrannosaurus Including Its Highly Divergent Species Specific Supraorbital Display Ornaments That Give T. rex a New and Unique Life Appearance

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2022, Номер unknown

Опубликована: Авг. 5, 2022

Abstract Intrageneric dinosaur species have been being named for decades without either significant examination of the methods and standards used to do so, or widely publicized controversy over results. The long standing assumption that all large known specimens iconic North American Tyrannosaurus consisted just one popular T. rex was recently challenged with first comprehensive test question. result diagnosing naming two additional taxa, imperator regina, based on a number levels characters regarding robustness tooth proportions in context their stratigraphic distribution. In association rare in-depth look taken at current state vertebrate paleospecies, which it turns out are not highly rigorous because inherent problems concept other matters. results paper were severely criticized manner never seen before new even when less evidence. This study takes another as determination shows many claims made criticisms work inaccurate. New data strength bars skulls reinforces basing three part factors, allows but skull be assigned species. These allow detailed systematic supraorbital display bosses genus. They sort visually distinctive specific ornaments both taxonomic strongly affirm multispecific, probably dimorphic. show sported – males -- striking yet observed tyrannosaurids.

Язык: Английский

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