Tyrannosaur Family Tree Flashcards
EASC 103: The Rise and Fall of the Dinosaurs - Lecture 13: Tyrannosaur Family Tree
Learning Goals
- Understand tyrannosaur phylogeny and its well-known members.
- The next lecture is about T-rex specifically.
Tyrannosaur Genera Covered
- Guanlong
- Dilong
- Yutyrannus
- Daspletosaurus
- Gorgosaurus
- Albertosaurus
- Tarbosaurus
Summary of the Tyrannosaur Family Tree
- In-class activity will focus on summarizing the tyrannosaur family tree.
Theropod Phylogeny
- Theropods are categorized into:
- Coelurosauria
- Tetanurans
- Non-tetanurans
- Non-coelurosaur tetanurans
- Examples:
- Carnotaurus: non-tetanuran
- Baryonyx: non-coelurosaur tetanuran
- Basal theropods and neotheropods exist.
Coelurosauria
- Coelurosaurs include:
- Therizinosaurs
- Oviraptorosaurs
- Dromaeosaurs
- Troodontids
- Avialae
- Higher ranking clades have additional evolutionary novelties ('more derived').
- Guanlong is an early member of Tyrannosauroidea.
Feathered Integument
- Evidence of feathered integument is found in all coelurosaur clades, including:
- Tyrannosauroidea
- Compsognathidae
- Ornithomimosauria
- Alvarezsauroidea
- Therizinosauria
- Oviraptorosauria
- Dromaeosauridae
- Troodontidae
- Avialae
Tyrannosauroidea
- Tyrannosauridae characteristics include:
- Reduction in forelimb size.
- Reduction in digits from 3 to 2.
- Early members of Proceratosauridae and the lineage leading to Tyrannosauridae show protofeathers.
Guanlong
- Guanlong ("crowned dragon") is an early proceratosaurid from China, dating back 160 Ma.
- Named for its large, thin crest.
- Known from 2 specimens found together.
Guanlong Discovery
- Discovered in the Junggar Basin of northern China in 'Death Trap' pits.
- One mudstone pit contained 5 stacked dinosaurs.
Guanlong 'Death Trap'
- Swampy environment where sauropods walking made the ground liquid, creating a quicksand-like trap.
Xu Xing
- Guanlong was discovered and named by paleontologist Xu Xing.
- Xu Xing stands at 33 named genera.
- Other named dinosaurs by Xu Xing:
- Dilong & Yutyrannus (tyrannosauroidea)
- Beipaiosaurus (therizinosauria)
- Gigantoraptor (oviraptorosauria)
- Mei long (troodontidae)
- Microraptor (dromaeosauridae)
- Most of Xu's discoveries are from the Yixian Formation of Liaoning Province in northern China.
- These Early Cretaceous (~125 Ma) beds are a treasure trove of fossils with exquisite preservation.
Dilong
- Dilong ("emperor dragon") is another theropod from the Yixian Formation, also known from 2 specimens.
- The holotype is a nearly complete, semi-articulated skeleton.
- Dilong was discovered with preservation of a feathered integument.
Yutyrannus
- Yutyrannus ("feathered tyrant") is also named by Xu Xing from the Early Cretaceous Yixian Formation.
- It reached 9 meters in length.
- Known from 3 specimens preserving integument in patches.
- Yutyrannus had a shaggy coat of long proto-feathers.
Tyrannosauridae Branches
- Tyrannosaurids are divided into gracile and robust branches.
Daspletosaurus & Gorgosaurus
- 75 million years ago, western North America was inhabited by two tyrannosaurids:
- Daspletosaurus ("frightful lizard") - Robust.
- Gorgosaurus ("fierce lizard") - Gracile.
Albertosaurus
- 5 million years later, Albertosaurus ("Alberta lizard") is found in North America around 70 Ma; it is a gracile tyrannosaurid.
Tarbosaurus
- Tarbosaurus ("alarming lizard") is a robust tyrannosaurid from Mongolia around 70 Ma (Gobi Desert).
- Smaller than Tyrannosaurus rex with a narrower skull and shorter forelimbs.
Theropod Lips?
- Tarbosaurus is depicted with lips in Prehistoric Planet.
- Debate on whether theropods had firm lips like an iguana or bared teeth like a crocodile.
Tyrannosaur Summary Table
| Name | Meaning | Lived When and Where | Proceratosauridae or Tyrannosauridae | Characteristics |
|---|
| Guanlong | Crowned Dragon | | | |
| Dilong | Emperor Dragon | | | |
| Yutyrannus | Feathered Tyrant | | | |
| Daspletosaurus | Frightful Lizard | | | |
| Gorgosaurus | Fierce Lizard | | | |
| Albertosaurus | Alberta Lizard | | | |
| Tarbosaurus | Alarming Lizard | | | |
Tyrannosaur Family Tree Diagram (Simplified)
- Diagram showing the phylogenetic relationships among various tyrannosaurs including:
- Kileskus
- Proceratosaurus
- Guanlong
- Stokesosaurus
- Juratyrant
- Yutyrannus
- Sinotyrannus
- Dilong
- Eotyrannus
- Xiongguanlong
- Dryptosaurus
- Raptorex
- Appalachiosaurus
- Bistahieversor
- Gorgosaurus
- Albertosaurus
- Alioramus (remotus & altai)
- Qianzhousaurus
- Nanuqsaurus
- Teratophoneus
- Lythronax
- Daspletosaurus (various species)
- Zhuchengtyrannus
- Tarbosaurus
- Tyrannosaurus
- Timescale from Jurassic to late Cretaceous.
Review Questions
- What do these terms mean:
- non-tetanuran vs tetanuran
- coelurosaur vs non-coelurosaur tetanuran
- Coelurosaurs inherited furcula and a large, complicated air sac system, but also gained additional evolutionary novelties.
- What are the terms used for feathers going from least to most complex?
- How do proceratosauridae and tyrannosauridae differ?
- Which tyrannosaurs we looked at belong to proceratosauridae? Were there any at the end of the Cretaceous belonging to this branch?
- Where does Dilong fit in to the tyrannosaur family tree?
- Describe Guanlong. What does the name mean? When and where did it live? How did the two specimens die?
- Many of Xu Xing’s genera are from the Yixian Formation. What is the age and location of this deposit?
- Describe Dilong and Yutyrannus. What do the names mean? When and where did they live? What is special about their discoveries?
- Which tyrannosaurids are gracile and which are robust? When and where did each live and what do the names mean?