Phylogeny of cenohadrosaurs

The information here is mostly **FICTIONAL**. Do not be fooled!

The **phylogeny of cenohadrosaurs** refers to the schemes used by researchers to classify cenohadrosaurs.

Cenohadrosaurs as a clade were only recognized in the twenty-first century, and as such cenohadrosaur researchers were able to use modern techniques such as cladistics from the very beginning of their discipline. Both traditional fieldwork and (in some cases) time travel are used to collect molecular and skeletal data from cenohadrosaurs, which are then input into a computer in order to determine their relationships.

It is unanimously agreed that all Cenozoic hadrosaurs belong to a monophyletic Cenohadrosauria. However, despite the abundance and quality of data, much disagreement exists over their internal relationships. They are traditionally divided into two major subclades, the hollow-crested Neolambeosauria and the usually solid-crested Neosaurolophia; however, several alternative ideas have been proposed. For example, the basal Neoaralosauria (=Archaeocenohadrosauria) and the Neotsintaosauridae have been recovered as potential third clades, and the Neosaurolophia was seen as potentially paraphyletic leading to Neolambeosauria. These major subclades have also been subdivided into smaller families, including Neoparasaurolophidae and Neoedmontosauridae. While their compositions usually remain stable, the greater interrelationships of these families have been subject of great debate.

Certain hypotheses about cenohadrosaur phylogeny are sometimes referred to as "matrices", after the phylogenetic data matrices that software processes to make phylogenetic trees. Matrices are named with numbers reflecting the order in which they were proposed; matrices with multiple variations are further distinguished by letters (e.g. Matrix 8a). To date, over sixty different matrices have been proposed.

The sections below present a selection of different phylogenetic hypotheses proposed for cenohadrosaurs over time, derived from different matrices, with modern clade names added for clarity.

## Tree 1

This tree was generated for the description of *Fragilihadros diaphoros*, using Matrix 8a. It depicts the traditional hierarchy of cenohadrosaurs, with a monophyletic Neosaurolophia+Neolambeosauria split. The former clade consists of (Neobrachylophosauridae+(Neokritosauridae+(Neosaurolophidae+Neoedmontosauridae))), while the latter contains the families Neoarenysauridae, Neoparasaurolophidae, and Neolambeosauridae, the last of which includes Neotsintaosaurinae and Microcenohadrosauria. Paleontologists have noted that this arrangement almost completely parallels the hierarchy of the euhadrosaurs, but later studies (see below) do not recover such an exact correspondence.

**1** = Cenohadrosauria, **2** = Eucenohadrosauria, **3** = Neosaurolophia, **4** = Neobrachylophosauridae, **5** = Neoedmontosauridae **6** = Neolambeosauria, **7** = Neolambeosauridae

## Tree 2

This tree was generated for the description of *Macrinsulahadros arkhaios*, using Matrix 21b. The general topology is mostly traditional, but differs from earlier topologies in that Neokritosauridae are more closely related to Neoedmontosauridae than Neosaurolophidae; additionally, unlike later topologies, the basalmost taxa are the neohadrosaurians instead of *Dikastisaurus* and *Ischiohadros*. Neolambeosauria has been collapsed to just the clade names for clarity.

**1** = Cenohadrosauria, **2** = Neobrachylophosauria, **3** = Eucenohadrosauria, **4** = Neosaurolophia, **5** = Neoedmontosauridae, **6** = Neolambeosauria

## Tree 3

This tree was generated for the description of *Bellorestes juvenilis*, using Matrix 30. *Dikastisaurus* and *Ischiohadros* now form a clade at the base of Cenohadrosauria, *Ovicardia* is a basal neokritosaurid, Neokritosauridae is once again more basal than Neosaurolophidae and Neoedmontosauridae, while the neolambeosaurs are slightly rearranged, with traditional neotsintaosaurs being paraphyletic. The neolambeosaurs have been condensed for clarity.

**1** = Cenohadrosauria, **2** = Eucenohadrosauria, **3** = Neosaurolophia, **4** = Neobrachylophosauridae, **5** = Neoedmontosauridae, **6** = Neolambeosauria, **7** = Neotsintaosauridae

## Tree 4

This tree was generated for the description of *Augustosaurus agriochortus*, using Matrix 39. It shows three major clades, Neoaralosauria, Neolambeosauria, and Neosaurolophia, with the last being "traditionally" arranged. The neolambeosaurs have been condensed for clarity.

**1** = Cenohadrosauria, **2** = Eucenohadrosauria, **3** = Neosaurolophia, **4** = Neoedmontosauridae, **5** = Neolambeosauria, **6** = Neoparasaurolophidae, **7** = Neolambeosauridae

## Tree 5

This tree was generated for the description of *Macrosteon musculus*, using Matrix 52. The neolambeosaurs have been condensed for clarity.

**1** = Cenohadrosauria, **2** = Neoaralosauria/Archaeocenohadrosauria, **3** = Eucenohadrosauria, **4** = Neosaurolophia, **5** = Neolambeosauria, **6** = Neoparasaurolophidae, **7** = Neolambeosauridae