I have a class based on `TimeStampedModel` from `django-extentions`:

```
from model_utils.models import TimeStampedModel

class MyClass(TimeStampedModel):
    pass

```

By default in the admin interface the `created` and `modified` fields are not displayed in the edition page `my_app/myclass/id`.

I tried this hack to force the display of the `created` and `modified` fields in the edit admin page for `MyClass`:

```
from django.contrib import admin

from my_app.models import MyClass

class MyClassAdmin(admin.ModelAdmin):
    fields = MyClass._meta.get_all_field_names()

admin.site.register(MyClass, MyClassAdmin)

```

But this raised the following exception:

```
Exception Type:     FieldError
Exception Value:    Unknown field(s) (modified, created) specified for MyClass. Check fields/fieldsets/exclude attributes of class MyClassAdmin.

```

Any idea how can I display the `created` and `modified` fields in the `MyClass` edition admin interface?

**Note 1:** `MyClass` is a model with a lot of fields including `ManyToMany` fields. I can display all the fields except the `created` and `modified` fields from the base class `TimeStampedModel`.

**Note 2:** The admin page in reference is the edition page of a row: `my_app/myclass/id`