Tyrannotitan

{{Short description|Carcharodontosaurid dinosaur genus from the early Cretaceous}}

{{Automatic taxobox

| fossil_range = Early Cretaceous (Albian), {{fossilrange|113|100.5|earliest=121|latest=112}}

| image = Tyrannotitan in Queensland Museum.jpg

| image_caption = Reconstructed skeleton in Queensland Museum

| taxon = Tyrannotitan

| authority = Novas et al., 2005

| type_species = {{extinct}}Tyrannotitan chubutensis

| subdivision =

| type_species_authority = Novas et al., 2005

}}

Tyrannotitan ({{IPAc-en|t|ᵻ|ˌ|r|æ|n|ə|ˈ|t|aɪ|t|ə|n}}; {{lit|tyrant titan}}) is a genus of large theropod dinosaur belonging to the carcharodontosaurid family. It is known from a single species, T. chubutensis, which lived during the Albian stage of the Early Cretaceous period in what is now Argentina. Tyrannotitan is considered a close relative of other giant carcharodontosaurids from Gondwana, such as Carcharodontosaurus, but it shares an especially close relationship with the South American carcharodontosaurids Giganotosaurus and Mapusaurus. Tyrannotitan is known from a few specimens, however none of them are very complete.

Discovery and species

File:Tyrannotitan remains 01.png

File:Fosiles Tyrannotitan 01.JPG

Tyrannotitan chubutensis was described by Fernando E. Novas, Silvina de Valais, Pat Vickers-Rich, and Tom Rich in 2005. The fossils were found at La Juanita Farm, {{convert|28|km}} northeast of Paso de Indios, Chubut Province, Argentina. They are believed to have been from the Cerro Castaño Member, Cerro Barcino Formation (Albian stage).{{cite journal|last=Novas|first=F. E.|author2=S. de Valais |author3=P. Vickers-Rich |author4=T. Rich |year=2005|title= A large Cretaceous theropod from Patagonia, Argentina, and the evolution of carcharodontosaurids|journal=Naturwissenschaften|volume=92|issue=5|pages= 226–230|doi=10.1007/s00114-005-0623-3|pmid=15834691|bibcode=2005NW.....92..226N|s2cid=24015414|hdl=11336/103474|hdl-access=free}}

The holotype material was designated MPEF-PV 1156 and included partial dentaries, teeth, back vertebrae 3–8 and 11–14, proximal tail vertebrae, ribs and chevrons, a fragmentary scapulocoracoid, humerus, ulna, partial ilium, a nearly complete femur, fibula, and left metatarsal 2. Additional material (designated MPEF-PV 1157) included jugals, a right dentary, teeth, atlas vertebra, neck vertebra (?) 9, back vertebrae (?)7, 10, 13, fused sacral centra (5 total), an assortment of distal caudals, ribs, the right femur, a fragmentary left metatarsal 2, pedal phalanges 2-1, 2–2, and 3-3.

Description

File:Tyrannotitan.jpg]]

File:Tyrannotitan Scale.svg

Tyrannotitan was a large animal, reaching {{convert|11.6|m|ft}} in length and {{cvt|6|-|7.4|MT|ST}} in body mass.{{cite book |vauthors=Rey LV, Holtz, Jr TR |title=Dinosaurs: the most complete, up-to-date encyclopedia for dinosaur lovers of all ages |url=https://archive.org/details/dinosaursmostcom00holt |publisher=Random House |place=United States of America |year=2007 |isbn=978-0-375-82419-7 |url-access=registration }}{{cite book |author=Gregory S. Paul |title=The Princeton Field Guide to Dinosaurs |publisher=Princeton University Press |place=United States of America |year=2010 |isbn=9780691137209 |url-access=registration |url=https://archive.org/details/princetonfieldgu0000paul }}{{Cite journal|last1=Campione|first1=Nicolás E.|last2=Evans|first2=David C.|date=2020|title=The accuracy and precision of body mass estimation in non-avian dinosaurs|journal=Biological Reviews|language=en|volume=95|issue=6|pages=1759–1797|doi=10.1111/brv.12638|pmid=32869488|s2cid=221404013|issn=1469-185X|doi-access=free}}{{cite journal|title=Nicolás E. Campione, David C. Evans, Caleb M. Brown, Matthew T. Carrano (2014). Body mass estimation in non-avian bipeds using a theoretical conversion to quadruped stylopodial proportions |journal=Methods in Ecology and Evolution|volume=5|issue=9|pages=913–923|doi=10.1111/2041-210X.12226|year=2014|last1=Campione|first1=Nicolás E.|last2=Evans|first2=David C.|last3=Brown|first3=Caleb M.|last4=Carrano|first4=Matthew T.|s2cid=84317234|doi-access=free|bibcode=2014MEcEv...5..913C }}{{Cite journal |last1=Persons |first1=S. W. |last2=Currie |first2=P. J. |last3=Erickson |first3=G. M. |title=An Older and Exceptionally Large Adult Specimen of Tyrannosaurus rex |journal=The Anatomical Record |volume=303 |issue=4 |pages=656–672 |doi=10.1002/ar.24118 |pmid=30897281 |issn=1932-8486|year=2020 |doi-access=free }} Its vertebral column is extensively pneumatized, with pneumatic openings in the dorsal and caudal vertebrae resembling those of Giganotosaurus and Mapusaurus. More unusually, Tyrannotitan shows a pneumatic hiatus in the anterior sacral region, a gap in the invasive pneumaticity of different portions of the vertebral column that were pneumatized by independent segments of the respiratory system (air sacs or their diverticula). Such gaps are most commonly observed in juvenile individuals, whose skeletal pneumaticity has not yet fully developed.{{Cite journal |last1=Melstrom |first1=Keegan M. |last2=D'emic |first2=Michael D. |last3=Chure |first3=Daniel |last4=Wilson |first4=Jeffrey A. |date=2016-07-03 |title=A juvenile sauropod dinosaur from the Late Jurassic of Utah, U.S.A., presents further evidence of an avian style air-sac system |url=https://www.tandfonline.com/doi/full/10.1080/02724634.2016.1111898 |journal=Journal of Vertebrate Paleontology |language=en |volume=36 |issue=4 |pages=e1111898 |doi=10.1080/02724634.2016.1111898 |bibcode=2016JVPal..36E1898M |issn=0272-4634|url-access=subscription }}

The scapulocoracoid is fused, and much better developed than that of Giganotosaurus carolinii, yet the arm is very small. Most of the shaft of the scapula is missing. The acromion curves about 90 degrees from the shaft axis, making it look vaguely tyrannosaurid-like. Whether the sharp difference between taxa is due to evolution or sexual dimorphism in poorly sampled populations of both species, has not been determined (the latter seems unlikely). A proximal caudal has a very tall neural spine (about twice the height of its centrum, judging by the figure). The base of the orbital fenestra is a notch of nearly 90 degrees into the body of the jugal, which contrasts with the rounded base restored for Giganotosaurus and agrees with Carcharodontosaurus favorably. The denticles on its teeth are "chisel-like", and are virtually identical to those of other carcharodontosaurids in having a wrinkled enamel surface, heavily serrated mesial and distal carinae, and labiolingually compressed (laterally flattened) crowns.{{cite journal|journal=Historical Biology|volume=27|pages=1–32|doi=10.1080/08912963.2013.861830|year=2015|last1=Canale|first1=Juan Ignacio|title=Osteology and phylogenetic relationships of Tyrannotitan chubutensis Novas, de Valais, Vickers-Rich and Rich, 2005 (Theropoda: Carcharodontosauridae) from the Lower Cretaceous of Patagonia, Argentina|last2=Novas|first2=Fernando Emilio|last3=Pol|first3=Diego|issue=1 |bibcode=2015HBio...27....1C |hdl=11336/17607 |s2cid=84583928|hdl-access=free}} The femur of the paratype specimen is {{cvt|1.4|m|ft}} long according to Novas et al. Canale et al. recover Tyrannotitan as deeply nested within the tribe Giganotosaurini as its most basal member. Characteristics that unite the Giganotosaurini include the presence of a postorbital process on the jugal with a wide base, and a derived femur with a weak fourth trochanter and a shallow broad extensor groove at the distal end.{{Cite journal |date=2006 |title=A new carcharodontosaurid (Dinosauria, Theropoda) from the Upper Cretaceous of Argentina |url=https://sciencepress.mnhn.fr/en/periodiques/geodiversitas/28/1/un-nouveau-carcharodontosauride-dinosauria-theropoda-du-cretace-superieur-d-argentine |journal=Geodiversitas |language=en |volume=28 |issue=1 |pages=71–118}}

Paleoecology

Tyrannotitan chubutensis lived during the Albian stage of the Early Cretaceous period, approximately 113 to 100 million years ago, in what is now the Cerro Castaño Member of the Cerro Barcino Formation in Chubut Province, Argentina. This region was part of Gondwana and featured a variety of environments, including river systems, floodplains, and semi-arid areas interspersed with scattered forests. The warm climate and abundant water sources, such as rivers and lakes, supported a diverse ecosystem that included large herbivorous dinosaurs, smaller theropods, and other fauna. {{Cite web |date=2021-06-08 |title=Tyrannotitan chubutensis {{!}} Dinosaur Database by DinoAnimals.com |url=https://dinoanimals.com/dinosaurdatabase/tyrannotitan-chubutensis/ |access-date=2025-01-13 |website=dinoanimals.com |language=en-US}}{{cite journal |url=https://staff.mef.org.ar/images/investigadores/diego_pol/papers/72.pdf |title= Osteology and phylogenetic relationships of Tyrannotitan chubutensis Novas, de Valais, Vickers-Rich and Rich, 2005 (Theropoda: Carcharodontosauridae) from the Lower Cretaceous of Patagonia, Argentina |journal=Historical Biology |volume=27 |issue=1 |year=2013 |publication-date=2015 |doi=10.1080/08912963.2013.861830 |last1= Canale |first1= Juan Ignacio |last2= Novas |first2= Fernando Emilio |last3= Pol |first3= Diego |pages= 1–32 |hdl= 11336/17607 }}

As an apex predator, Tyrannotitan likely played a significant role in shaping its ecosystem. Its diet primarily consisted of large herbivorous dinosaurs such as Chubutisaurus and possibly juveniles or weaker individuals of massive sauropods like Patagotitan. These interactions highlight its position at the top of the food chain. Evidence suggests that Tyrannotitan may have been an active hunter, using its powerful bite and robust dentition to subdue prey, though it may also have scavenged opportunistically.{{Cite web |last=Duhamel |first=Dr Alienor |date=2024-05-25 |title=Tyrannotitan {{!}} Colossal Predator of the Early Cretaceous |url=https://thedinosaurs.org/dinosaurs/tyrannotitan |access-date=2025-01-13 |website=The Dinosaurs |language=en-US}}{{Cite web |title=Tyrannotitan |url=https://dinosaurpictures.org/Tyrannotitan-pictures |access-date=2025-01-13 |website=dinosaurpictures.org |language=en}}

Some studies propose that Tyrannotitan may have exhibited adaptations for ambush hunting near water sources. Its proximity to rivers and swamps not only provided cooling opportunities but also facilitated access to prey seeking refuge near these habitats. The possibility of social behavior remains speculative; however, tracksite evidence from other large theropods in Gondwana suggests that some degree of interaction or grouping behavior might have occurred.{{Cite journal |last1=Moreno |first1=Karen |last2=Valais |first2=Silvina de |last3=Blanco |first3=Nicolás |last4=Tomlinson |first4=Andrew J. |last5=Jacay |first5=Javier |last6=Calvo |first6=Jorge O. |date=March 2012 |title=Large Theropod Dinosaur Footprint Associations in Western Gondwana: Behavioural and Palaeogeographic Implications |url=https://bioone.org/journals/acta-palaeontologica-polonica/volume-57/issue-1/app.2010.0119/Large-Theropod-Dinosaur-Footprint-Associations-in-Western-Gondwana--Behavioural/10.4202/app.2010.0119.full |journal=Acta Palaeontologica Polonica |language=en |volume=57 |issue=1 |pages=73–83 |doi=10.4202/app.2010.0119 |issn=0567-7920 |archive-url=http://web.archive.org/web/20240415123750/https://bioone.org/journals/acta-palaeontologica-polonica/volume-57/issue-1/app.2010.0119/Large-Theropod-Dinosaur-Footprint-Associations-in-Western-Gondwana--Behavioural/10.4202/app.2010.0119.full |archive-date=2024-04-15}}

Classification

In their 2022 description of the large carcharodontosaurine Meraxes. Canale et al. recovered Tyrannotitan within the clade Giganotosaurini, along with Meraxes, Giganotosaurus, and Mapusaurus. The results of their phylogenetic analyses are shown in the cladogram below:{{cite journal |last1=Canale |first1=Juan I. |last2=Apesteguía |first2=Sebastián |last3=Gallina |first3=Pablo A. |last4=Mitchell |first4=Jonathan |last5=Smith |first5=Nathan D. |last6=Cullen |first6=Thomas M. |last7=Shinya |first7=Akiko |last8=Haluza |first8=Alejandro |last9=Gianechini |first9=Federico A. |last10=Makovicky |first10=Peter J. |title=New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction |journal=Current Biology |date=July 2022 |volume=32 |issue=14 |pages=3195–3202.e5 |doi=10.1016/j.cub.2022.05.057 |pmid=35803271 |s2cid=250343124 |doi-access=free |bibcode=2022CBio...32E3195C }}

{{clade|{{clade

|1=Neovenator

75px

|2={{clade

|1=Concavenator 75px

|2=Eocarcharia

65px

|3=Lajasvenator

|4=Lusovenator

|5={{clade

|1=Acrocanthosaurus

75px

|2={{clade

|1=Shaochilong

80px

|label2=Carcharodontosaurinae

|2={{clade

|1=Carcharodontosaurus spp.

75px

|label2=Giganotosaurini

|2={{clade

|1=Meraxes

75px

|2={{clade

|1=Tyrannotitan

|2={{clade

|1=Giganotosaurus

75px

|2=Mapusaurus

80px

}} }} }} }} }} }} }} }}|label1=Carcharodontosauridae}}

In his 2024 review of theropod relationships, Cau found similar relationships for Tyrannotitan. His results are shown below:{{cite journal |last1=Cau |first1=Andrea |title=A Unified Framework for Predatory Dinosaur Macroevolution |journal=Bollettino della Società Paleontologica Italiana |date=2024 |volume=63 |issue=1 |pages=1–19 |doi=10.4435/BSPI.2024.08 |doi-broken-date=20 November 2024 |url=https://www.paleoitalia.it/wp-content/uploads/2024/04/Cau_2024_BSPI_ONLINE.pdf |access-date=1 May 2024 |archive-date=27 April 2024 |archive-url=https://web.archive.org/web/20240427205522/https://www.paleoitalia.it/wp-content/uploads/2024/04/Cau_2024_BSPI_ONLINE.pdf |url-status=dead }}{{clade|{{clade

|1=Neovenator

75px

|2={{clade

|1={{clade

|1=Sauroniops

|2=Veterupristisaurus

|3=Lusovenator

|4=Eocarcharia {{small|(type skull roof)}}

65px

|5=Concavenator 75px

}}

|2={{clade